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authorAlex Shi <alex.shi@linux.alibaba.com>2021-02-24 23:09:25 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-25 00:38:34 +0300
commitd99fd5feb0ac1d56c36c760a8d922a46bd6c5521 (patch)
tree2e22ddedd1e89d0eef7aa78f4a357605bd8b803a /mm/compaction.c
parentc457cd96f18c7137287700c409d2ae16c6395256 (diff)
downloadlinux-d99fd5feb0ac1d56c36c760a8d922a46bd6c5521.tar.xz
mm/compaction: remove rcu_read_lock during page compaction
isolate_migratepages_block() used rcu_read_lock() with the intention of safeguarding against the mem_cgroup being destroyed concurrently; but its TestClearPageLRU already protects against that. Delete the unnecessary rcu_read_lock() and _unlock(). Hugh Dickins helped on commit log polishing, Thanks! Link: https://lkml.kernel.org/r/1608614453-10739-3-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/compaction.c')
-rw-r--r--mm/compaction.c5
1 files changed, 1 insertions, 4 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 3aef10c61d0e..69ca3d6f9764 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -995,7 +995,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
if (!TestClearPageLRU(page))
goto isolate_fail_put;
- rcu_read_lock();
lruvec = mem_cgroup_page_lruvec(page, pgdat);
/* If we already hold the lock, we can skip some rechecking */
@@ -1005,7 +1004,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
compact_lock_irqsave(&lruvec->lru_lock, &flags, cc);
locked = lruvec;
- rcu_read_unlock();
lruvec_memcg_debug(lruvec, page);
@@ -1026,8 +1024,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
SetPageLRU(page);
goto isolate_fail_put;
}
- } else
- rcu_read_unlock();
+ }
/* The whole page is taken off the LRU; skip the tail pages. */
if (PageCompound(page))