diff options
| author | Johannes Weiner <hannes@cmpxchg.org> | 2021-02-24 12:04:15 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-24 13:38:30 -0800 |
| commit | 6eeb104e114cb6b7391c2d69ff873403858c1f35 (patch) | |
| tree | 5ed91e4614aaff0ed676995ad2f2db9761ae361a /mm/memcontrol.c | |
| parent | a7b7e1df892457935ec4f35ef9e9aa344758dbc9 (diff) | |
| download | linux-6eeb104e114cb6b7391c2d69ff873403858c1f35.tar.bz2 | |
fs: buffer: use raw page_memcg() on locked page
alloc_page_buffers() currently uses get_mem_cgroup_from_page() for
charging the buffers to the page owner, which does an rcu-protected
page->memcg lookup and acquires a reference. But buffer allocation has
the page lock held throughout, which pins the page to the memcg and
thereby the memcg - neither rcu nor holding an extra reference during the
allocation are necessary. Use a raw page_memcg() instead.
This was the last user of get_mem_cgroup_from_page(), delete it.
Link: https://lkml.kernel.org/r/20210209190126.97842-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.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>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 23 |
1 files changed, 0 insertions, 23 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8c035846c7a4..7fdc001ce15f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1047,29 +1047,6 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) } EXPORT_SYMBOL(get_mem_cgroup_from_mm); -/** - * get_mem_cgroup_from_page: Obtain a reference on given page's memcg. - * @page: page from which memcg should be extracted. - * - * Obtain a reference on page->memcg and returns it if successful. Otherwise - * root_mem_cgroup is returned. - */ -struct mem_cgroup *get_mem_cgroup_from_page(struct page *page) -{ - struct mem_cgroup *memcg = page_memcg(page); - - if (mem_cgroup_disabled()) - return NULL; - - rcu_read_lock(); - /* Page should not get uncharged and freed memcg under us. */ - if (!memcg || WARN_ON_ONCE(!css_tryget(&memcg->css))) - memcg = root_mem_cgroup; - rcu_read_unlock(); - return memcg; -} -EXPORT_SYMBOL(get_mem_cgroup_from_page); - static __always_inline struct mem_cgroup *active_memcg(void) { if (in_interrupt()) |