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* mm/z3fold.c: limit first_num to the actual range of possible buddy indexeszhong jiang2017-02-221-3/+7
| | | | | | | | | | | | | | | | At present, Tying the first_num size to NCHUNKS_ORDER is confusing. the number of chunks is completely unrelated to the number of buddies. The patch limits the first_num to actual range of possible buddy indexes. and that is more reasonable and obvious without functional change. Link: http://lkml.kernel.org/r/1476776569-29504-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhong jiang <zhongjiang@huawei.com> Suggested-by: Dan Streetman <ddstreet@ieee.org> Acked-by: Dan Streetman <ddstreet@ieee.org> Acked-by: Vitaly Wool <vitalywool@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/memblock.c: remove unnecessary log and clean upMiles Chen2017-02-221-29/+25
| | | | | | | | | | | | | There is no variable named flags in memblock_add() and memblock_reserve() so remove it from the log messages. This patch also cleans up the type casting for phys_addr_t by using %pa to print them. Link: http://lkml.kernel.org/r/1484720165-25403-1-git-send-email-miles.chen@mediatek.com Signed-off-by: Miles Chen <miles.chen@mediatek.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* oom-reaper: use madvise_dontneed() logic to decide if unmap the VMAKirill A. Shutemov2017-02-223-9/+9
| | | | | | | | | | | | | | | | | | Logic on whether we can reap pages from the VMA should match what we have in madvise_dontneed(). In particular, we should skip, VM_PFNMAP VMAs, but we don't now. Let's just extract condition on which we can shoot down pagesi from a VMA with MADV_DONTNEED into separate function and use it in both places. Link: http://lkml.kernel.org/r/20170118122429.43661-4-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: drop unused argument of zap_page_range()Kirill A. Shutemov2017-02-222-4/+3
| | | | | | | | | | | | | | There's no users of zap_page_range() who wants non-NULL 'details'. Let's drop it. Link: http://lkml.kernel.org/r/20170118122429.43661-3-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: drop zap_details::check_swap_entriesKirill A. Shutemov2017-02-222-4/+3
| | | | | | | | | | | | | | detail == NULL would give the same functionality as .check_swap_entries==true. Link: http://lkml.kernel.org/r/20170118122429.43661-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: drop zap_details::ignore_dirtyKirill A. Shutemov2017-02-222-8/+1
| | | | | | | | | | | | | | | | | | The only user of ignore_dirty is oom-reaper. But it doesn't really use it. ignore_dirty only has effect on file pages mapped with dirty pte. But oom-repear skips shared VMAs, so there's no way we can dirty file pte in them. Link: http://lkml.kernel.org/r/20170118122429.43661-1-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, page_alloc: warn_alloc nodemask is NULL when cpusets are disabledDavid Rientjes2017-02-221-3/+7
| | | | | | | | | | | | | | | | | | | | | | The patch "mm, page_alloc: warn_alloc print nodemask" implicitly sets the allocation nodemask to cpuset_current_mems_allowed when there is no effective mempolicy. cpuset_current_mems_allowed is only effective when cpusets are enabled, which is also printed by warn_alloc(), so setting the nodemask to cpuset_current_mems_allowed is redundant and prevents debugging issues where ac->nodemask is not set properly in the page allocator. This provides better debugging output since cpuset_print_current_mems_allowed() is already provided. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701181347320.142399@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: help __GFP_NOFAIL allocations which do not trigger OOM killerMichal Hocko2017-02-221-10/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that __GFP_NOFAIL doesn't override decisions to skip the oom killer we are left with requests which require to loop inside the allocator without invoking the oom killer (e.g. GFP_NOFS|__GFP_NOFAIL used by fs code) and so they might, in very unlikely situations, loop for ever - e.g. other parallel request could starve them. This patch tries to limit the likelihood of such a lockup by giving these __GFP_NOFAIL requests a chance to move on by consuming a small part of memory reserves. We are using ALLOC_HARDER which should be enough to prevent from the starvation by regular allocation requests, yet it shouldn't consume enough from the reserves to disrupt high priority requests (ALLOC_HIGH). While we are at it, let's introduce a helper __alloc_pages_cpuset_fallback which enforces the cpusets but allows to fallback to ignore them if the first attempt fails. __GFP_NOFAIL requests can be considered important enough to allow cpuset runaway in order for the system to move on. It is highly unlikely that any of these will be GFP_USER anyway. Link: http://lkml.kernel.org/r/20161220134904.21023-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, oom: do not enforce OOM killer for __GFP_NOFAIL automaticallyMichal Hocko2017-02-222-26/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __alloc_pages_may_oom makes sure to skip the OOM killer depending on the allocation request. This includes lowmem requests, costly high order requests and others. For a long time __GFP_NOFAIL acted as an override for all those rules. This is not documented and it can be quite surprising as well. E.g. GFP_NOFS requests are not invoking the OOM killer but GFP_NOFS|__GFP_NOFAIL does so if we try to convert some of the existing open coded loops around allocator to nofail request (and we have done that in the past) then such a change would have a non trivial side effect which is far from obvious. Note that the primary motivation for skipping the OOM killer is to prevent from pre-mature invocation. The exception has been added by commit 82553a937f12 ("oom: invoke oom killer for __GFP_NOFAIL"). The changelog points out that the oom killer has to be invoked otherwise the request would be looping for ever. But this argument is rather weak because the OOM killer doesn't really guarantee a forward progress for those exceptional cases: - it will hardly help to form costly order which in turn can result in the system panic because of no oom killable task in the end - I believe we certainly do not want to put the system down just because there is a nasty driver asking for order-9 page with GFP_NOFAIL not realizing all the consequences. It is much better this request would loop for ever than the massive system disruption - lowmem is also highly unlikely to be freed during OOM killer - GFP_NOFS request could trigger while there is still a lot of memory pinned by filesystems. This patch simply removes the __GFP_NOFAIL special case in order to have a more clear semantic without surprising side effects. Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Nils Holland <nholland@tisys.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: consolidate GFP_NOFAIL checks in the allocator slowpathMichal Hocko2017-02-221-39/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tetsuo Handa has pointed out that commit 0a0337e0d1d1 ("mm, oom: rework oom detection") has subtly changed semantic for costly high order requests with __GFP_NOFAIL and withtout __GFP_REPEAT and those can fail right now. My code inspection didn't reveal any such users in the tree but it is true that this might lead to unexpected allocation failures and subsequent OOPs. __alloc_pages_slowpath wrt. GFP_NOFAIL is hard to follow currently. There are few special cases but we are lacking a catch all place to be sure we will not miss any case where the non failing allocation might fail. This patch reorganizes the code a bit and puts all those special cases under nopage label which is the generic go-to-fail path. Non failing allocations are retried or those that cannot retry like non-sleeping allocation go to the failure point directly. This should make the code flow much easier to follow and make it less error prone for future changes. While we are there we have to move the stall check up to catch potentially looping non-failing allocations. [akpm@linux-foundation.org: fix alloc_flags may-be-used-uninitalized] Link: http://lkml.kernel.org/r/20161220134904.21023-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/show_mem.c: teach show_mem to work with the given nodemaskMichal Hocko2017-02-223-23/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | show_mem() allows to filter out node specific data which is irrelevant to the allocation request via SHOW_MEM_FILTER_NODES. The filtering is done in skip_free_areas_node which skips all nodes which are not in the mems_allowed of the current process. This works most of the time as expected because the nodemask shouldn't be outside of the allocating task but there are some exceptions. E.g. memory hotplug might want to request allocations from outside of the allowed nodes (see new_node_page). Get rid of this hardcoded behavior and push the allocation mask down the show_mem path and use it instead of cpuset_current_mems_allowed. NULL nodemask is interpreted as cpuset_current_mems_allowed. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170117091543.25850-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, page_alloc: warn_alloc print nodemaskMichal Hocko2017-02-222-6/+8
| | | | | | | | | | | | | | | | | | | | warn_alloc is currently used for to report an allocation failure or an allocation stall. We print some details of the allocation request like the gfp mask and the request order. We do not print the allocation nodemask which is important when debugging the reason for the allocation failure as well. We alreaddy print the nodemask in the OOM report. Add nodemask to warn_alloc and print it in warn_alloc as well. Link: http://lkml.kernel.org/r/20170117091543.25850-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, page_alloc: do not report all nodes in show_memMichal Hocko2017-02-221-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "show_mem updates", v2. This is a mixture of one bug fix (patch 1), an enhancement (patch 2) and cleanups (the rest of the series). First two patches should be really straightforward. Patch 3 removes some arch specific show_mem implementations because I think they are quite outdated and do not really serve any useful purpose anymore. I think we should really strive to have a consistent show_mem output regardless of the architecture. If some architecture is really special and wants to dump something additional we should do that via an arch specific hook. The last patch adds nodemask parameter so that we do not rely on the hardcoded mems_allowed of the current task when doing the node filtering. I consider this more a cleanup than a fix because basically all users use a nodemask which is a subset of mems_allowed. There is only one call path in the memory hotplug which doesn't comply with this but that is hardly something to worry about. This patch (of 4): Commit 599d0c954f91 ("mm, vmscan: move LRU lists to node") has added per numa node statistics to show_mem but it forgot to add skip_free_areas_node to filter out nodes which are outside of the allocating task numa policy. Add this check to not pollute the output with the pointless information. Link: http://lkml.kernel.org/r/20170117091543.25850-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Revert "mm: bail out in shrink_inactive_list()"Michal Hocko2017-02-221-27/+0
| | | | | | | | | | | | | | | | | This reverts commit 91dcade47a3d0e7. inactive_reclaimable_pages shouldn't be needed anymore since that get_scan_count is aware of the eligble zones ("mm, vmscan: consider eligible zones in get_scan_count"). Link: http://lkml.kernel.org/r/20170117103702.28542-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpchxg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: consider eligible zones in get_scan_countMichal Hocko2017-02-221-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | get_scan_count() considers the whole node LRU size when - doing SCAN_FILE due to many page cache inactive pages - calculating the number of pages to scan In both cases this might lead to unexpected behavior especially on 32b systems where we can expect lowmem memory pressure very often. A large highmem zone can easily distort SCAN_FILE heuristic because there might be only few file pages from the eligible zones on the node lru and we would still enforce file lru scanning which can lead to trashing while we could still scan anonymous pages. The later use of lruvec_lru_size can be problematic as well. Especially when there are not many pages from the eligible zones. We would have to skip over many pages to find anything to reclaim but shrink_node_memcg would only reduce the remaining number to scan by SWAP_CLUSTER_MAX at maximum. Therefore we can end up going over a large LRU many times without actually having chance to reclaim much if anything at all. The closer we are out of memory on lowmem zone the worse the problem will be. Fix this by filtering out all the ineligible zones when calculating the lru size for both paths and consider only sc->reclaim_idx zones. The patch would need to be tweaked a bit to apply to 4.10 and older but I will do that as soon as it hits the Linus tree in the next merge window. Link: http://lkml.kernel.org/r/20170117103702.28542-3-mhocko@kernel.org Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis") Signed-off-by: Michal Hocko <mhocko@suse.com> Tested-by: Trevor Cordes <trevor@tecnopolis.ca> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: cleanup lru size claculationsMichal Hocko2017-02-222-46/+45
| | | | | | | | | | | | | | | | | lruvec_lru_size returns the full size of the LRU list while we sometimes need a value reduced only to eligible zones (e.g. for lowmem requests). inactive_list_is_low is one such user. Later patches will add more of them. Add a new parameter to lruvec_lru_size and allow it filter out zones which are not eligible for the given context. Link: http://lkml.kernel.org/r/20170117103702.28542-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: do not count freed pages as PGDEACTIVATEMichal Hocko2017-02-221-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | PGDEACTIVATE represents the number of pages moved from the active list to the inactive list. At least this sounds like the original motivation of the counter. move_active_pages_to_lru, however, counts pages which got freed in the mean time as deactivated as well. This is a very rare event and counting them as deactivation in itself is not harmful but it makes the code more convoluted than necessary - we have to count both all pages and those which are freed which is a bit confusing. After this patch the PGDEACTIVATE should have a slightly more clear semantic and only count those pages which are moved from the active to the inactive list which is a plus. Link: http://lkml.kernel.org/r/20170112211221.17636-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/backing-dev.c: use rb_entry()Geliang Tang2017-02-221-2/+2
| | | | | | | | | | | | To make the code clearer, use rb_entry() instead of container_of() to deal with rbtree. Link: http://lkml.kernel.org/r/671275de093d93ddc7c6f77ddc0d357149691a39.1484306840.git.geliangtang@gmail.com Signed-off-by: Geliang Tang <geliangtang@gmail.com> Cc: Jens Axboe <axboe@fb.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, thp: add new defer+madvise defrag optionDavid Rientjes2017-02-221-72/+74
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is no thp defrag option that currently allows MADV_HUGEPAGE regions to do direct compaction and reclaim while all other thp allocations simply trigger kswapd and kcompactd in the background and fail immediately. The "defer" setting simply triggers background reclaim and compaction for all regions, regardless of MADV_HUGEPAGE, which makes it unusable for our userspace where MADV_HUGEPAGE is being used to indicate the application is willing to wait for work for thp memory to be available. The "madvise" setting will do direct compaction and reclaim for these MADV_HUGEPAGE regions, but does not trigger kswapd and kcompactd in the background for anybody else. For reasonable usage, there needs to be a mesh between the two options. This patch introduces a fifth mode, "defer+madvise", that will do direct reclaim and compaction for MADV_HUGEPAGE regions and trigger background reclaim and compaction for everybody else so that hugepages may be available in the near future. A proposal to allow direct reclaim and compaction for MADV_HUGEPAGE regions as part of the "defer" mode, making it a very powerful setting and avoids breaking userspace, was offered: http://marc.info/?t=148236612700003 This additional mode is a compromise. A second proposal to allow both "defer" and "madvise" to be selected at the same time was also offered: http://marc.info/?t=148357345300001. This is possible, but there was a concern that it might break existing userspaces the parse the output of the defrag mode, so the fifth option was introduced instead. This patch also cleans up the helper function for storing to "enabled" and "defrag" since the former supports three modes while the latter supports five and triple_flag_store() was getting unnecessarily messy. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701101614330.41805@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: skip readahead only when swap slot cache is enabledHuang Ying2017-02-222-4/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Because during swap off, a swap entry may have swap_map[] == SWAP_HAS_CACHE (for example, just allocated). If we return NULL in __read_swap_cache_async(), the swap off will abort. So when swap slot cache is disabled, (for swap off), we will wait for page to be put into swap cache in such race condition. This should not be a problem for swap slot cache, because swap slot cache should be drained after clearing swap_slot_cache_enabled. [ying.huang@intel.com: fix memory leak in __read_swap_cache_async()] Link: http://lkml.kernel.org/r/874lzt6znd.fsf@yhuang-dev.intel.com Link: http://lkml.kernel.org/r/5e2c5f6abe8e6eb0797408897b1bba80938e9b9d.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: enable swap slots cache usageTim Chen2017-02-221-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | Initialize swap slots cache and enable it on swap on. Drain all swap slots on swap off. Link: http://lkml.kernel.org/r/07cbc94882fa95d4ac3cfc50b8dce0b1ec231b93.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: add cache for swap slots allocationTim Chen2017-02-224-12/+359
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We add per cpu caches for swap slots that can be allocated and freed quickly without the need to touch the swap info lock. Two separate caches are maintained for swap slots allocated and swap slots returned. This is to allow the swap slots to be returned to the global pool in a batch so they will have a chance to be coaelesced with other slots in a cluster. We do not reuse the slots that are returned right away, as it may increase fragmentation of the slots. The swap allocation cache is protected by a mutex as we may sleep when searching for empty slots in cache. The swap free cache is protected by a spin lock as we cannot sleep in the free path. We refill the swap slots cache when we run out of slots, and we disable the swap slots cache and drain the slots if the global number of slots fall below a low watermark threshold. We re-enable the cache agian when the slots available are above a high watermark. [ying.huang@intel.com: use raw_cpu_ptr over this_cpu_ptr for swap slots access] [tim.c.chen@linux.intel.com: add comments on locks in swap_slots.h] Link: http://lkml.kernel.org/r/20170118180327.GA24225@linux.intel.com Link: http://lkml.kernel.org/r/35de301a4eaa8daa2977de6e987f2c154385eb66.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Michal Hocko <mhocko@suse.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: free swap slots in batchTim Chen2017-02-221-61/+94
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Add new functions that free unused swap slots in batches without the need to reacquire swap info lock. This improves scalability and reduce lock contention. Link: http://lkml.kernel.org/r/c25e0fcdfd237ec4ca7db91631d3b9f6ed23824e.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: allocate swap slots in batchesTim Chen2017-02-221-25/+111
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the swap slots are allocated one page at a time, causing contention to the swap_info lock protecting the swap partition on every page being swapped. This patch adds new functions get_swap_pages and scan_swap_map_slots to request multiple swap slots at once. This will reduces the lock contention on the swap_info lock. Also scan_swap_map_slots can operate more efficiently as swap slots often occurs in clusters close to each other on a swap device and it is quicker to allocate them together. Link: http://lkml.kernel.org/r/9fec2845544371f62c3763d43510045e33d286a6.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: skip readahead for unreferenced swap slotsTim Chen2017-02-222-6/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | We can avoid needlessly allocating page for swap slots that are not used by anyone. No pages have to be read in for these slots. Link: http://lkml.kernel.org/r/0784b3f20b9bd3aa5552219624cb78dc4ae710c9.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: split swap cache into 64MB trunksHuang, Ying2017-02-223-20/+70
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The patch is to improve the scalability of the swap out/in via using fine grained locks for the swap cache. In current kernel, one address space will be used for each swap device. And in the common configuration, the number of the swap device is very small (one is typical). This causes the heavy lock contention on the radix tree of the address space if multiple tasks swap out/in concurrently. But in fact, there is no dependency between pages in the swap cache. So that, we can split the one shared address space for each swap device into several address spaces to reduce the lock contention. In the patch, the shared address space is split into 64MB trunks. 64MB is chosen to balance the memory space usage and effect of lock contention reduction. The size of struct address_space on x86_64 architecture is 408B, so with the patch, 6528B more memory will be used for every 1GB swap space on x86_64 architecture. One address space is still shared for the swap entries in the same 64M trunks. To avoid lock contention for the first round of swap space allocation, the order of the swap clusters in the initial free clusters list is changed. The swap space distance between the consecutive swap clusters in the free cluster list is at least 64M. After the first round of allocation, the swap clusters are expected to be freed randomly, so the lock contention should be reduced effectively. Link: http://lkml.kernel.org/r/735bab895e64c930581ffb0a05b661e01da82bc5.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: add cluster lockHuang, Ying2017-02-221-42/+173
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch is to reduce the lock contention of swap_info_struct->lock via using a more fine grained lock in swap_cluster_info for some swap operations. swap_info_struct->lock is heavily contended if multiple processes reclaim pages simultaneously. Because there is only one lock for each swap device. While in common configuration, there is only one or several swap devices in the system. The lock protects almost all swap related operations. In fact, many swap operations only access one element of swap_info_struct->swap_map array. And there is no dependency between different elements of swap_info_struct->swap_map. So a fine grained lock can be used to allow parallel access to the different elements of swap_info_struct->swap_map. In this patch, a spinlock is added to swap_cluster_info to protect the elements of swap_info_struct->swap_map in the swap cluster and the fields of swap_cluster_info. This reduced locking contention for swap_info_struct->swap_map access greatly. Because of the added spinlock, the size of swap_cluster_info increases from 4 bytes to 8 bytes on the 64 bit and 32 bit system. This will use additional 4k RAM for every 1G swap space. Because the size of swap_cluster_info is much smaller than the size of the cache line (8 vs 64 on x86_64 architecture), there may be false cache line sharing between spinlocks in swap_cluster_info. To avoid the false sharing in the first round of the swap cluster allocation, the order of the swap clusters in the free clusters list is changed. So that, the swap_cluster_info sharing the same cache line will be placed as far as possible. After the first round of allocation, the order of the clusters in free clusters list is expected to be random. So the false sharing should be not serious. Compared with a previous implementation using bit_spin_lock, the sequential swap out throughput improved about 3.2%. Test was done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case created 32 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used. [ying.huang@intel.com: v5] Link: http://lkml.kernel.org/r/878tqeuuic.fsf_-_@yhuang-dev.intel.com [minchan@kernel.org: initialize spinlock for swap_cluster_info] Link: http://lkml.kernel.org/r/1486434945-29753-1-git-send-email-minchan@kernel.org [hughd@google.com: annotate nested locking for cluster lock] Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1702161050540.21773@eggly.anvils Link: http://lkml.kernel.org/r/dbb860bbd825b1aaba18988015e8963f263c3f0d.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: fix kernel message in swap_info_get()Huang, Ying2017-02-221-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm/swap: Regular page swap optimizations", v5. Times have changed. Coming generation of Solid state Block device latencies are getting down to sub 100 usec, which is within an order of magnitude of DRAM, and their performance is orders of magnitude higher than the single- spindle rotational media we've swapped to historically. This could benefit many usage scenearios. For example cloud providers who overcommit their memory (as VM don't use all the memory provisioned). Having a fast swap will allow them to be more aggressive in memory overcommit and fit more VMs to a platform. In our testing [see footnote], the median latency that the kernel adds to a page fault is 15 usec, which comes quite close to the amount that will be contributed by the underlying I/O devices. The software latency comes mostly from contentions on the locks protecting the radix tree of the swap cache and also the locks protecting the individual swap devices. The lock contentions already consumed 35% of cpu cycles in our test. In the very near future, software latency will become the bottleneck to swap performnace as block device I/O latency gets within the shouting distance of DRAM speed. This patch set, reduced the median page fault latency from 15 usec to 4 usec (375% reduction) for DRAM based pmem block device. This patch (of 9): swap_info_get() is used not only in swap free code path but also in page_swapcount(), etc. So the original kernel message in swap_info_get() is not correct now. Fix it via replacing "swap_free" to "swap_info_get" in the message. Link: http://lkml.kernel.org/r/9b5f8bd6266f9da978c373f2384c8044df5e262c.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* powerpc: do not make the entire heap executableDenys Vlasenko2017-02-221-5/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On 32-bit powerpc the ELF PLT sections of binaries (built with --bss-plt, or with a toolchain which defaults to it) look like this: [17] .sbss NOBITS 0002aff8 01aff8 000014 00 WA 0 0 4 [18] .plt NOBITS 0002b00c 01aff8 000084 00 WAX 0 0 4 [19] .bss NOBITS 0002b090 01aff8 0000a4 00 WA 0 0 4 Which results in an ELF load header: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align LOAD 0x019c70 0x00029c70 0x00029c70 0x01388 0x014c4 RWE 0x10000 This is all correct, the load region containing the PLT is marked as executable. Note that the PLT starts at 0002b00c but the file mapping ends at 0002aff8, so the PLT falls in the 0 fill section described by the load header, and after a page boundary. Unfortunately the generic ELF loader ignores the X bit in the load headers when it creates the 0 filled non-file backed mappings. It assumes all of these mappings are RW BSS sections, which is not the case for PPC. gcc/ld has an option (--secure-plt) to not do this, this is said to incur a small performance penalty. Currently, to support 32-bit binaries with PLT in BSS kernel maps *entire brk area* with executable rights for all binaries, even --secure-plt ones. Stop doing that. Teach the ELF loader to check the X bit in the relevant load header and create 0 filled anonymous mappings that are executable if the load header requests that. Test program showing the difference in /proc/$PID/maps: int main() { char buf[16*1024]; char *p = malloc(123); /* make "[heap]" mapping appear */ int fd = open("/proc/self/maps", O_RDONLY); int len = read(fd, buf, sizeof(buf)); write(1, buf, len); printf("%p\n", p); return 0; } Compiled using: gcc -mbss-plt -m32 -Os test.c -otest Unpatched ppc64 kernel: 00100000-00120000 r-xp 00000000 00:00 0 [vdso] 0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094 /usr/lib/libc-2.17.so 0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094 /usr/lib/libc-2.17.so 0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094 /usr/lib/libc-2.17.so 10000000-10010000 r-xp 00000000 fd:00 100674505 /home/user/test 10010000-10020000 r--p 00000000 fd:00 100674505 /home/user/test 10020000-10030000 rw-p 00010000 fd:00 100674505 /home/user/test 10690000-106c0000 rwxp 00000000 00:00 0 [heap] f7f70000-f7fa0000 r-xp 00000000 fd:00 67898089 /usr/lib/ld-2.17.so f7fa0000-f7fb0000 r--p 00020000 fd:00 67898089 /usr/lib/ld-2.17.so f7fb0000-f7fc0000 rw-p 00030000 fd:00 67898089 /usr/lib/ld-2.17.so ffa90000-ffac0000 rw-p 00000000 00:00 0 [stack] 0x10690008 Patched ppc64 kernel: 00100000-00120000 r-xp 00000000 00:00 0 [vdso] 0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094 /usr/lib/libc-2.17.so 0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094 /usr/lib/libc-2.17.so 0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094 /usr/lib/libc-2.17.so 10000000-10010000 r-xp 00000000 fd:00 100674505 /home/user/test 10010000-10020000 r--p 00000000 fd:00 100674505 /home/user/test 10020000-10030000 rw-p 00010000 fd:00 100674505 /home/user/test 10180000-101b0000 rw-p 00000000 00:00 0 [heap] ^^^^ this has changed f7c60000-f7c90000 r-xp 00000000 fd:00 67898089 /usr/lib/ld-2.17.so f7c90000-f7ca0000 r--p 00020000 fd:00 67898089 /usr/lib/ld-2.17.so f7ca0000-f7cb0000 rw-p 00030000 fd:00 67898089 /usr/lib/ld-2.17.so ff860000-ff890000 rw-p 00000000 00:00 0 [stack] 0x10180008 The patch was originally posted in 2012 by Jason Gunthorpe and apparently ignored: https://lkml.org/lkml/2012/9/30/138 Lightly run-tested. Link: http://lkml.kernel.org/r/20161215131950.23054-1-dvlasenk@redhat.com Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Florian Weimer <fweimer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/memory_hotplug: set magic number to page->freelist instead of page->lru.nextYasuaki Ishimatsu2017-02-222-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To identify that pages of page table are allocated from bootmem allocator, magic number sets to page->lru.next. But page->lru list is initialized in reserve_bootmem_region(). So when calling free_pagetable(), the function cannot find the magic number of pages. And free_pagetable() frees the pages by free_reserved_page() not put_page_bootmem(). But if the pages are allocated from bootmem allocator and used as page table, the pages have private flag. So before freeing the pages, we should clear the private flag by put_page_bootmem(). Before applying the commit 7bfec6f47bb0 ("mm, page_alloc: check multiple page fields with a single branch"), we could find the following visible issue: BUG: Bad page state in process kworker/u1024:1 page:ffffea103cfd8040 count:0 mapcount:0 mappi flags: 0x6fffff80000800(private) page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set bad because of flags: 0x800(private) <snip> Call Trace: [...] dump_stack+0x63/0x87 [...] bad_page+0x114/0x130 [...] free_pages_prepare+0x299/0x2d0 [...] free_hot_cold_page+0x31/0x150 [...] __free_pages+0x25/0x30 [...] free_pagetable+0x6f/0xb4 [...] remove_pagetable+0x379/0x7ff [...] vmemmap_free+0x10/0x20 [...] sparse_remove_one_section+0x149/0x180 [...] __remove_pages+0x2e9/0x4f0 [...] arch_remove_memory+0x63/0xc0 [...] remove_memory+0x8c/0xc0 [...] acpi_memory_device_remove+0x79/0xa5 [...] acpi_bus_trim+0x5a/0x8d [...] acpi_bus_trim+0x38/0x8d [...] acpi_device_hotplug+0x1b7/0x418 [...] acpi_hotplug_work_fn+0x1e/0x29 [...] process_one_work+0x152/0x400 [...] worker_thread+0x125/0x4b0 [...] kthread+0xd8/0xf0 [...] ret_from_fork+0x22/0x40 And the issue still silently occurs. Until freeing the pages of page table allocated from bootmem allocator, the page->freelist is never used. So the patch sets magic number to page->freelist instead of page->lru.next. [isimatu.yasuaki@jp.fujitsu.com: fix merge issue] Link: http://lkml.kernel.org/r/722b1cc4-93ac-dd8b-2be2-7a7e313b3b0b@gmail.com Link: http://lkml.kernel.org/r/2c29bd9f-5b67-02d0-18a3-8828e78bbb6f@gmail.com Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Xishi Qiu <qiuxishi@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/sparse: use page_private() to get page->private valueYasuaki Ishimatsu2017-02-221-1/+1
| | | | | | | | | | | | | | | | | | | | | free_map_bootmem() uses page->private directly to set removing_section_nr argument. But to get page->private value, page_private() has been prepared. So free_map_bootmem() should use page_private() instead of page->private. Link: http://lkml.kernel.org/r/1d34eaa5-a506-8b7a-6471-490c345deef8@gmail.com Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Xishi Qiu <qiuxishi@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/memblock.c: check return value of memblock_reserve() in ↵Wei Yang2017-02-221-4/+2
| | | | | | | | | | | | | | | | | | | | | | memblock_virt_alloc_internal() memblock_reserve() would add a new range to memblock.reserved in case the new range is not totally covered by any of the current memblock.reserved range. If the memblock.reserved is full and can't resize, memblock_reserve() would fail. This doesn't happen in real world now, I observed this during code review. While theoretically, it has the chance to happen. And if it happens, others would think this range of memory is still available and may corrupt the memory. This patch checks the return value and goto "done" after it succeeds. Link: http://lkml.kernel.org/r/1482363033-24754-3-git-send-email-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/memblock.c: trivial code refine in memblock_is_region_memory()Wei Yang2017-02-221-2/+1
| | | | | | | | | | | | | | | | | | memblock_is_region_memory() invoke memblock_search() to see whether the base address is in the memory region. If it fails, idx would be -1. Then, it returns 0. If the memblock_search() returns a valid index, it means the base address is guaranteed to be in the range memblock.memory.regions[idx]. Because of this, it is not necessary to check the base again. This patch removes the check on "base". Link: http://lkml.kernel.org/r/1482363033-24754-2-git-send-email-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix some typos in mm/zsmalloc.cXishi Qiu2017-02-221-3/+3
| | | | | | | | | | | Delete extra semicolon, and fix some typos. Link: http://lkml.kernel.org/r/586F1823.4050107@huawei.com Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/bootmem.c: cosmetic improvement of code readabilityAdygzhy Ondar2017-02-221-1/+1
| | | | | | | | | | The obvious number of bits in a byte is replaced by BITS_PER_BYTE macro in bootmap_bytes() Link: http://lkml.kernel.org/r/1483781600-5136-1-git-send-email-ondar07@gmail.com Signed-off-by: Adygzhy Ondar <ondar07@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm,compaction: serialize waitqueue_active() checksDavidlohr Bueso2017-02-221-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Without a memory barrier, the following race can occur with a high-order allocation: wakeup_kcompactd(order == 1) kcompactd() [L] waitqueue_active(kcompactd_wait) [S] prepare_to_wait_event(kcompactd_wait) [L] (kcompactd_max_order == 0) [S] kcompactd_max_order = order; schedule() Where the waitqueue_active() check is speculatively re-ordered to before setting the actual condition (max_order), not seeing the threads that's going to block; making us miss a wakeup. There are a couple of options to fix this, including calling wq_has_sleepers() which adds a full barrier, or unconditionally doing the wake_up_interruptible() and serialize on the q->lock. However, to make use of the control dependency, we just need to add L->L guarantees. While this bug is theoretical, there have been other offenders of the lockless waitqueue_active() in the past -- this is also documented in the call itself. Link: http://lkml.kernel.org/r/1483975528-24342-1-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: page_alloc: skip over regions of invalid pfns where possiblePaul Burton2017-02-222-1/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | When using a sparse memory model memmap_init_zone() when invoked with the MEMMAP_EARLY context will skip over pages which aren't valid - ie. which aren't in a populated region of the sparse memory map. However if the memory map is extremely sparse then it can spend a long time linearly checking each PFN in a large non-populated region of the memory map & skipping it in turn. When CONFIG_HAVE_MEMBLOCK_NODE_MAP is enabled, we have sufficient information to quickly discover the next valid PFN given an invalid one by searching through the list of memory regions & skipping forwards to the first PFN covered by the memory region to the right of the non-populated region. Implement this in order to speed up memmap_init_zone() for systems with extremely sparse memory maps. James said "I have tested this patch on a virtual model of a Samurai CPU with a sparse memory map. The kernel boot time drops from 109 to 62 seconds. " Link: http://lkml.kernel.org/r/20161125185518.29885-1-paul.burton@imgtec.com Signed-off-by: Paul Burton <paul.burton@imgtec.com> Tested-by: James Hartley <james.hartley@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, compaction: add vmstats for kcompactd workDavid Rientjes2017-02-223-3/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | A "compact_daemon_wake" vmstat exists that represents the number of times kcompactd has woken up. This doesn't represent how much work it actually did, though. It's useful to understand how much compaction work is being done by kcompactd versus other methods such as direct compaction and explicitly triggered per-node (or system) compaction. This adds two new vmstats: "compact_daemon_migrate_scanned" and "compact_daemon_free_scanned" to represent the number of pages kcompactd has scanned as part of its migration scanner and freeing scanner, respectively. These values are still accounted for in the general "compact_migrate_scanned" and "compact_free_scanned" for compatibility. It could be argued that explicitly triggered compaction could also be tracked separately, and that could be added if others find it useful. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1612071749390.69852@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mmzone.c: swap likely to unlikely as code logic is different for ↵Steven Rostedt2017-02-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | next_zones_zonelist() Commit 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator") changed how next_zones_zonelist() is called, by adding a static inline function to do the fast path. This function adds: if (likely(!nodes && zonelist_zone_idx(z) <= highest_zoneidx)) return z; return __next_zones_zonelist(z, highest_zoneidx, nodes); Where __next_zones_zonelist() is only called when nodes is not NULL or zonelist_zone_idx(z) is less than highest_zoneidx. The original next_zone_zonelist() was converted to __next_zones_zonelist() but it still maintained: if (likely(nodes == NULL)) Which is now actually a very unlikely, as it is only called with nodes equal to NULL when zonelist_zone_idx(z) is greater than highest_zoneidx. Before this commit, this if had this statistic: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 837895 446078 34 next_zones_zonelist mmzone.c 63 After this commit, it has: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 10 173840 99 __next_zones_zonelist mmzone.c 63 Thus, the if statement is now much more unlikely than it ever was as a likely. Link: http://lkml.kernel.org/r/20170105200102.77989567@gandalf.local.home Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix filemap.c kernel-doc warningsRandy Dunlap2017-02-221-1/+1
| | | | | | | | | | | | Fix kernel-doc warnings in mm/filemap.c: mm/filemap.c:993: warning: No description found for parameter '__page' mm/filemap.c:993: warning: Excess function parameter 'page' description in '__lock_page' Link: http://lkml.kernel.org/r/a66fe492-518c-ad6c-5f03-5e8b721fb451@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: un-export wake_up_page functionsNicholas Piggin2017-02-221-2/+8
| | | | | | | | | | | | | These are no longer used outside mm/filemap.c, so un-export them and make them static where possible. These were exported specifically for NFS use in commit a4796e37c12e ("MM: export page_wakeup functions"). Link: http://lkml.kernel.org/r/20170103182234.30141-3-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Cc: Trond Myklebust <trond.myklebust@primarydata.com> Cc: Anna Schumaker <anna.schumaker@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: add mm_vmscan_inactive_list_is_low tracepointMichal Hocko2017-02-221-9/+14
| | | | | | | | | | | | | | | | Currently we have tracepoints for both active and inactive LRU lists reclaim but we do not have any which would tell us why we we decided to age the active list. Without that it is quite hard to diagnose active/inactive lists balancing. Add mm_vmscan_inactive_list_is_low tracepoint to tell us this information. Link: http://lkml.kernel.org/r/20170104101942.4860-8-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepointMichal Hocko2017-02-221-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | mm_vmscan_lru_shrink_inactive will currently report the number of scanned and reclaimed pages. This doesn't give us an idea how the reclaim went except for the overall effectiveness though. Export and show other counters which will tell us why we couldn't reclaim some pages. - nr_dirty, nr_writeback, nr_congested and nr_immediate tells us how many pages are blocked due to IO - nr_activate tells us how many pages were moved to the active list - nr_ref_keep reports how many pages are kept on the LRU due to references (mostly for the file pages which are about to go for another round through the inactive list) - nr_unmap_fail - how many pages failed to unmap All these are rather low level so they might change in future but the tracepoint is already implementation specific so no tools should be depending on its stability. Link: http://lkml.kernel.org/r/20170104101942.4860-7-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: extract shrink_page_list reclaim counters into a structMichal Hocko2017-02-221-31/+30
| | | | | | | | | | | | | | | | | | | | shrink_page_list returns quite some counters back to its caller. Extract the existing 5 into struct reclaim_stat because this makes the code easier to follow and also allows further counters to be returned. While we are at it, make all of them unsigned rather than unsigned long as we do not really need full 64b for them (we never scan more than SWAP_CLUSTER_MAX pages at once). This should reduce some stack space. This patch shouldn't introduce any functional change. Link: http://lkml.kernel.org/r/20170104101942.4860-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepointMichal Hocko2017-02-221-2/+1
| | | | | | | | | | | | | | | | | | mm_vmscan_lru_isolate currently prints only whether the LRU we isolate from is file or anonymous but we do not know which LRU this is. It is useful to know whether the list is active or inactive, since we are using the same function to isolate pages from both of them and it's hard to distinguish otherwise. Link: http://lkml.kernel.org/r/20170104101942.4860-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolateMichal Hocko2017-02-221-6/+7
| | | | | | | | | | | | | | | | | | | mm_vmscan_lru_isolate shows the number of requested, scanned and taken pages. This is mostly OK but on 32b systems the number of scanned pages is quite misleading because it includes both the scanned and skipped pages. Moreover the skipped part is scaled based on the number of taken pages. Let's report the exact numbers without any additional logic and add the number of skipped pages. This should make the reported data much more easier to interpret. Link: http://lkml.kernel.org/r/20170104101942.4860-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: add active list aging tracepointMichal Hocko2017-02-221-4/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Our reclaim process has several tracepoints to tell us more about how things are progressing. We are, however, missing a tracepoint to track active list aging. Introduce mm_vmscan_lru_shrink_active which reports the number of - nr_taken is number of isolated pages from the active list - nr_referenced pages which tells us that we are hitting referenced pages which are deactivated. If this is a large part of the reported nr_deactivated pages then we might be hitting into the active list too early because they might be still part of the working set. This might help to debug performance issues. - nr_active pages which tells us how many pages are kept on the active list - mostly exec file backed pages. A high number can indicate that we might be trashing on executables. [mhocko@suse.com: update] Link: http://lkml.kernel.org/r/20170104135244.GJ25453@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170104101942.4860-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mprotect: use pmd_trans_unstable instead of taking the pmd_lockAndrea Arcangeli2017-02-221-31/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | pmd_trans_unstable does an atomic read on the pmd so it doesn't require the pmd_lock for the same check. This also removes the special assumption that the mmap_sem is hold for writing if prot_numa is not set. userfaultfd will hold the mmap_sem only for reading in change_pte_range like prot_numa, but it will not set prot_numa. This is always a valid micro-optimization regardless of userfaultfd. [kirill@shutemov.name: drop unneeded pmd_trans_unstable(pmd) check after __split_huge_pmd()] Link: http://lkml.kernel.org/r/20170208120421.GE5578@node.shutemov.name Link: http://lkml.kernel.org/r/20161216144821.5183-43-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michael Rapoport <RAPOPORT@il.ibm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userfaultfd: shmem: avoid leaking blocks and used blocks in UFFDIO_COPYAndrea Arcangeli2017-02-221-10/+13
| | | | | | | | | | | | | | | | | If the atomic copy_user fails because of a real dangling userland pointer, we won't go back into the shmem method, so when the method returns it must not leave anything charged up, except the page itself. Link: http://lkml.kernel.org/r/20161216144821.5183-37-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michael Rapoport <RAPOPORT@il.ibm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userfaultfd: shmem: avoid a lockup resulting from corrupted page->flagsAndrea Arcangeli2017-02-221-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use the non atomic version of __SetPageUptodate while the page is still private and not visible to lookup operations. Using the non atomic version after the page is already visible to lookups is unsafe as there would be concurrent lock_page operation modifying the page->flags while it runs. This solves a lockup in find_lock_entry with the userfaultfd_shmem selftest. userfaultfd_shm D14296 691 1 0x00000004 Call Trace: schedule+0x3d/0x90 schedule_timeout+0x228/0x420 io_schedule_timeout+0xa4/0x110 __lock_page+0x12d/0x170 find_lock_entry+0xa4/0x190 shmem_getpage_gfp+0xb9/0xc30 shmem_fault+0x70/0x1c0 __do_fault+0x21/0x150 handle_mm_fault+0xec9/0x1490 __do_page_fault+0x20d/0x520 trace_do_page_fault+0x61/0x270 do_async_page_fault+0x19/0x80 async_page_fault+0x25/0x30 Link: http://lkml.kernel.org/r/20170116180408.12184-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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