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authorMichal Hocko <mhocko@suse.com>2016-07-27 01:24:53 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-27 02:19:19 +0300
commit8a5c743e308dd2b90ad10d1faaa7a1b09173a132 (patch)
treeba679ecefc77b4a80bd35b00e55ddc1457b14e07 /fs/ext4/readpage.c
parente5e3f4c4f0e95ecbad2f8d2f4f6a29bb8a90226b (diff)
downloadlinux-8a5c743e308dd2b90ad10d1faaa7a1b09173a132.tar.xz
mm, memcg: use consistent gfp flags during readahead
Vladimir has noticed that we might declare memcg oom even during readahead because read_pages only uses GFP_KERNEL (with mapping_gfp restriction) while __do_page_cache_readahead uses page_cache_alloc_readahead which adds __GFP_NORETRY to prevent from OOMs. This gfp mask discrepancy is really unfortunate and easily fixable. Drop page_cache_alloc_readahead() which only has one user and outsource the gfp_mask logic into readahead_gfp_mask and propagate this mask from __do_page_cache_readahead down to read_pages. This alone would have only very limited impact as most filesystems are implementing ->readpages and the common implementation mpage_readpages does GFP_KERNEL (with mapping_gfp restriction) again. We can tell it to use readahead_gfp_mask instead as this function is called only during readahead as well. The same applies to read_cache_pages. ext4 has its own ext4_mpage_readpages but the path which has pages != NULL can use the same gfp mask. Btrfs, cifs, f2fs and orangefs are doing a very similar pattern to mpage_readpages so the same can be applied to them as well. [akpm@linux-foundation.org: coding-style fixes] [mhocko@suse.com: restrict gfp mask in mpage_alloc] Link: http://lkml.kernel.org/r/20160610074223.GC32285@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1465301556-26431-1-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Chris Mason <clm@fb.com> Cc: Steve French <sfrench@samba.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Jan Kara <jack@suse.cz> Cc: Mike Marshall <hubcap@omnibond.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Changman Lee <cm224.lee@samsung.com> Cc: Chao Yu <yuchao0@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ext4/readpage.c')
-rw-r--r--fs/ext4/readpage.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index dc54a4b60eba..c75b66a64982 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -166,7 +166,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
page = list_entry(pages->prev, struct page, lru);
list_del(&page->lru);
if (add_to_page_cache_lru(page, mapping, page->index,
- mapping_gfp_constraint(mapping, GFP_KERNEL)))
+ readahead_gfp_mask(mapping)))
goto next_page;
}