kernel/linux.git/mm, branch v4.10.2

mm, vmscan: consider eligible zones in get_scan_count

2017-03-12T05:44:10+00:00

commit 71ab6cfe88dcf9f6e6a65eb85cf2bda20a257682 upstream. 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 Tested-by: Trevor Cordes Acked-by: Minchan Kim Acked-by: Hillf Danton Acked-by: Mel Gorman Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm, vmscan: cleanup lru size claculations

2017-03-12T05:44:10+00:00

commit fd538803731e50367b7c59ce4ad3454426a3d671 upstream. 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 Acked-by: Johannes Weiner Acked-by: Hillf Danton Acked-by: Minchan Kim Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: do not access page->mapping directly on page_endio

2017-03-12T05:44:10+00:00

commit dd8416c47715cf324c9a16f13273f9fda87acfed upstream. With rw_page, page_endio is used for completing IO on a page and it propagates write error to the address space if the IO fails. The problem is it accesses page->mapping directly which might be okay for file-backed pages but it shouldn't for anonymous page. Otherwise, it can corrupt one of field from anon_vma under us and system goes panic randomly. swap_writepage bdev_writepage ops->rw_page I encountered the BUG during developing new zram feature and it was really hard to figure it out because it made random crash, somtime mmap_sem lockdep, sometime other places where places never related to zram/zsmalloc, and not reproducible with some configuration. When I consider how that bug is subtle and people do fast-swap test with brd, it's worth to add stable mark, I think. Fixes: dd6bd0d9c7db ("swap: use bdev_read_page() / bdev_write_page()") Signed-off-by: Minchan Kim Acked-by: Michal Hocko Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: vmpressure: fix sending wrong events on underflow

2017-03-12T05:44:10+00:00

commit e1587a4945408faa58d0485002c110eb2454740c upstream. At the end of a window period, if the reclaimed pages is greater than scanned, an unsigned underflow can result in a huge pressure value and thus a critical event. Reclaimed pages is found to go higher than scanned because of the addition of reclaimed slab pages to reclaimed in shrink_node without a corresponding increment to scanned pages. Minchan Kim mentioned that this can also happen in the case of a THP page where the scanned is 1 and reclaimed could be 512. Link: http://lkml.kernel.org/r/1486641577-11685-1-git-send-email-vinmenon@codeaurora.org Signed-off-by: Vinayak Menon Acked-by: Minchan Kim Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Mel Gorman Cc: Vlastimil Babka Cc: Rik van Riel Cc: Vladimir Davydov Cc: Anton Vorontsov Cc: Shiraz Hashim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/page_alloc: fix nodes for reclaim in fast path

2017-03-12T05:44:10+00:00

commit e02dc017c3032dcdce1b993af0db135462e1b4b7 upstream. When @node_reclaim_node isn't 0, the page allocator tries to reclaim pages if the amount of free memory in the zones are below the low watermark. On Power platform, none of NUMA nodes are scanned for page reclaim because no nodes match the condition in zone_allows_reclaim(). On Power platform, RECLAIM_DISTANCE is set to 10 which is the distance of Node-A to Node-A. So the preferred node even won't be scanned for page reclaim. __alloc_pages_nodemask() get_page_from_freelist() zone_allows_reclaim() Anton proposed the test code as below: # cat alloc.c : int main(int argc, char *argv[]) { void *p; unsigned long size; unsigned long start, end; start = time(NULL); size = strtoul(argv[1], NULL, 0); printf("To allocate %ldGB memory\n", size); size <<= 30; p = malloc(size); assert(p); memset(p, 0, size); end = time(NULL); printf("Used time: %ld seconds\n", end - start); sleep(3600); return 0; } The system I use for testing has two NUMA nodes. Both have 128GB memory. In below scnario, the page caches on node#0 should be reclaimed when it encounters pressure to accommodate request of allocation. # echo 2 > /proc/sys/vm/zone_reclaim_mode; \ sync; \ echo 3 > /proc/sys/vm/drop_caches; \ # taskset -c 0 cat file.32G > /dev/null; \ grep FilePages /sys/devices/system/node/node0/meminfo Node 0 FilePages: 33619712 kB # taskset -c 0 ./alloc 128 # grep FilePages /sys/devices/system/node/node0/meminfo Node 0 FilePages: 33619840 kB # grep MemFree /sys/devices/system/node/node0/meminfo Node 0 MemFree: 186816 kB With the patch applied, the pagecache on node-0 is reclaimed when its free memory is running out. It's the expected behaviour. # echo 2 > /proc/sys/vm/zone_reclaim_mode; \ sync; \ echo 3 > /proc/sys/vm/drop_caches # taskset -c 0 cat file.32G > /dev/null; \ grep FilePages /sys/devices/system/node/node0/meminfo Node 0 FilePages: 33605568 kB # taskset -c 0 ./alloc 128 # grep FilePages /sys/devices/system/node/node0/meminfo Node 0 FilePages: 1379520 kB # grep MemFree /sys/devices/system/node/node0/meminfo Node 0 MemFree: 317120 kB Fixes: 5f7a75acdb24 ("mm: page_alloc: do not cache reclaim distances") Link: http://lkml.kernel.org/r/1486532455-29613-1-git-send-email-gwshan@linux.vnet.ibm.com Signed-off-by: Gavin Shan Acked-by: Mel Gorman Acked-by: Michal Hocko Cc: Anton Blanchard Cc: Michael Ellerman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

block: fix double-free in the failure path of cgwb_bdi_init()

2017-02-26T10:09:19+00:00

commit 5f478e4ea5c5560b4e40eb136991a09f9389f331 upstream. When !CONFIG_CGROUP_WRITEBACK, bdi has single bdi_writeback_congested at bdi->wb_congested. cgwb_bdi_init() allocates it with kzalloc() and doesn't do further initialization. This usually works fine as the reference count gets bumped to 1 by wb_init() and the put from wb_exit() releases it. However, when wb_init() fails, it puts the wb base ref automatically freeing the wb and the explicit kfree() in cgwb_bdi_init() error path ends up trying to free the same pointer the second time causing a double-free. Fix it by explicitly initilizing the refcnt to 1 and putting the base ref from cgwb_bdi_destroy(). Signed-off-by: Tejun Heo Reported-by: Dmitry Vyukov Fixes: a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback") Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

mm/slub.c: fix random_seq offset destruction

2017-02-08T23:41:43+00:00

Commit 210e7a43fa90 ("mm: SLUB freelist randomization") broke USB hub initialisation as described in https://bugzilla.kernel.org/show_bug.cgi?id=177551. Bail out early from init_cache_random_seq if s->random_seq is already initialised. This prevents destroying the previously computed random_seq offsets later in the function. If the offsets are destroyed, then shuffle_freelist will truncate page->freelist to just the first object (orphaning the rest). Fixes: 210e7a43fa90 ("mm: SLUB freelist randomization") Link: http://lkml.kernel.org/r/20170207140707.20824-1-sean@erifax.org Signed-off-by: Sean Rees Reported-by: Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Thomas Garnier Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, fs: check for fatal signals in do_generic_file_read()

2017-02-03T22:13:19+00:00

do_generic_file_read() can be told to perform a large request from userspace. If the system is under OOM and the reading task is the OOM victim then it has an access to memory reserves and finishing the full request can lead to the full memory depletion which is dangerous. Make sure we rather go with a short read and allow the killed task to terminate. Link: http://lkml.kernel.org/r/20170201092706.9966-3-mhocko@kernel.org Signed-off-by: Michal Hocko Reviewed-by: Christoph Hellwig Cc: Tetsuo Handa Cc: Al Viro Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

base/memory, hotplug: fix a kernel oops in show_valid_zones()

2017-02-03T22:13:19+00:00

Reading a sysfs "memoryN/valid_zones" file leads to the following oops when the first page of a range is not backed by struct page. show_valid_zones() assumes that 'start_pfn' is always valid for page_zone(). BUG: unable to handle kernel paging request at ffffea017a000000 IP: show_valid_zones+0x6f/0x160 This issue may happen on x86-64 systems with 64GiB or more memory since their memory block size is bumped up to 2GiB. [1] An example of such systems is desribed below. 0x3240000000 is only aligned by 1GiB and this memory block starts from 0x3200000000, which is not backed by struct page. BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable Since test_pages_in_a_zone() already checks holes, fix this issue by extending this function to return 'valid_start' and 'valid_end' for a given range. show_valid_zones() then proceeds with the valid range. [1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")' Link: http://lkml.kernel.org/r/20170127222149.30893-3-toshi.kani@hpe.com Signed-off-by: Toshi Kani Cc: Greg Kroah-Hartman Cc: Zhang Zhen Cc: Reza Arbab Cc: David Rientjes Cc: Dan Williams Cc: [4.4+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()

2017-02-03T22:13:19+00:00

Patch series "fix a kernel oops when reading sysfs valid_zones", v2. A sysfs memory file is created for each 2GiB memory block on x86-64 when the system has 64GiB or more memory. [1] When the start address of a memory block is not backed by struct page, i.e. a memory range is not aligned by 2GiB, reading its 'valid_zones' attribute file leads to a kernel oops. This issue was observed on multiple x86-64 systems with more than 64GiB of memory. This patch-set fixes this issue. Patch 1 first fixes an issue in test_pages_in_a_zone(), which does not test the start section. Patch 2 then fixes the kernel oops by extending test_pages_in_a_zone() to return valid [start, end). Note for stable kernels: The memory block size change was made by commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems"), which was accepted to 3.9. However, this patch-set depends on (and fixes) the change to test_pages_in_a_zone() made by commit 5f0f2887f4de ("mm/memory_hotplug.c: check for missing sections in test_pages_in_a_zone()"), which was accepted to 4.4. So, I recommend that we backport it up to 4.4. [1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")' This patch (of 2): test_pages_in_a_zone() does not check 'start_pfn' when it is aligned by section since 'sec_end_pfn' is set equal to 'pfn'. Since this function is called for testing the range of a sysfs memory file, 'start_pfn' is always aligned by section. Fix it by properly setting 'sec_end_pfn' to the next section pfn. Also make sure that this function returns 1 only when the range belongs to a zone. Link: http://lkml.kernel.org/r/20170127222149.30893-2-toshi.kani@hpe.com Signed-off-by: Toshi Kani Cc: Andrew Banman Cc: Reza Arbab Cc: Greg KH Cc: [4.4+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds