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authorHugh Dickins <hughd@google.com>2020-09-18 21:20:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-09-19 13:13:38 -0700
commit8d8869ca5d2d9d86db96271ab063fdcfa9baf5b4 (patch)
treefcb754e1b13e38d078f75d701841d04f0de96322 /mm
parenta333e3e73b6648d3bd3ef6b971a59a6363bfcfc5 (diff)
mm: fix check_move_unevictable_pages() on THP
check_move_unevictable_pages() is used in making unevictable shmem pages evictable: by shmem_unlock_mapping(), drm_gem_check_release_pagevec() and i915/gem check_release_pagevec(). Those may pass down subpages of a huge page, when /sys/kernel/mm/transparent_hugepage/shmem_enabled is "force". That does not crash or warn at present, but the accounting of vmstats unevictable_pgs_scanned and unevictable_pgs_rescued is inconsistent: scanned being incremented on each subpage, rescued only on the head (since tails already appear evictable once the head has been updated). 5.8 commit 5d91f31faf8e ("mm: swap: fix vmstats for huge page") has established that vm_events in general (and unevictable_pgs_rescued in particular) should count every subpage: so follow that precedent here. Do this in such a way that if mem_cgroup_page_lruvec() is made stricter (to check page->mem_cgroup is always set), no problem: skip the tails before calling it, and add thp_nr_pages() to vmstats on the head. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Yang Shi <shy828301@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Qian Cai <cai@lca.pw> Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301405000.5954@eggly.anvils Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmscan.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9727dd8e2581..466fc3144fff 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4268,8 +4268,14 @@ void check_move_unevictable_pages(struct pagevec *pvec)
for (i = 0; i < pvec->nr; i++) {
struct page *page = pvec->pages[i];
struct pglist_data *pagepgdat = page_pgdat(page);
+ int nr_pages;
+
+ if (PageTransTail(page))
+ continue;
+
+ nr_pages = thp_nr_pages(page);
+ pgscanned += nr_pages;
- pgscanned++;
if (pagepgdat != pgdat) {
if (pgdat)
spin_unlock_irq(&pgdat->lru_lock);
@@ -4288,7 +4294,7 @@ void check_move_unevictable_pages(struct pagevec *pvec)
ClearPageUnevictable(page);
del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE);
add_page_to_lru_list(page, lruvec, lru);
- pgrescued++;
+ pgrescued += nr_pages;
}
}