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| author |   Alex Shi <alex.shi@linux.alibaba.com> | 2021-02-24 12:09:25 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-24 13:38:34 -0800 |
| commit | d99fd5feb0ac1d56c36c760a8d922a46bd6c5521 (patch) | |
| tree | 2e22ddedd1e89d0eef7aa78f4a357605bd8b803a /mm/compaction.c | |
| parent | z3fold: simplify the zhdr initialization code in init_z3fold_page() (diff) | |
| download | linux-dev-d99fd5feb0ac1d56c36c760a8d922a46bd6c5521.tar.xz linux-dev-d99fd5feb0ac1d56c36c760a8d922a46bd6c5521.zip | |
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.c | 5 |
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)) |