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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 /mm/readahead.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 'mm/readahead.c')
-rw-r--r--mm/readahead.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/mm/readahead.c b/mm/readahead.c
index 40be3ae0afe3..65ec288dc057 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -89,7 +89,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
page = lru_to_page(pages);
list_del(&page->lru);
if (add_to_page_cache_lru(page, mapping, page->index,
- mapping_gfp_constraint(mapping, GFP_KERNEL))) {
+ readahead_gfp_mask(mapping))) {
read_cache_pages_invalidate_page(mapping, page);
continue;
}
@@ -108,7 +108,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
EXPORT_SYMBOL(read_cache_pages);
static int read_pages(struct address_space *mapping, struct file *filp,
- struct list_head *pages, unsigned nr_pages)
+ struct list_head *pages, unsigned int nr_pages, gfp_t gfp)
{
struct blk_plug plug;
unsigned page_idx;
@@ -126,10 +126,8 @@ static int read_pages(struct address_space *mapping, struct file *filp,
for (page_idx = 0; page_idx < nr_pages; page_idx++) {
struct page *page = lru_to_page(pages);
list_del(&page->lru);
- if (!add_to_page_cache_lru(page, mapping, page->index,
- mapping_gfp_constraint(mapping, GFP_KERNEL))) {
+ if (!add_to_page_cache_lru(page, mapping, page->index, gfp))
mapping->a_ops->readpage(filp, page);
- }
put_page(page);
}
ret = 0;
@@ -159,6 +157,7 @@ int __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
int page_idx;
int ret = 0;
loff_t isize = i_size_read(inode);
+ gfp_t gfp_mask = readahead_gfp_mask(mapping);
if (isize == 0)
goto out;
@@ -180,7 +179,7 @@ int __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
if (page && !radix_tree_exceptional_entry(page))
continue;
- page = page_cache_alloc_readahead(mapping);
+ page = __page_cache_alloc(gfp_mask);
if (!page)
break;
page->index = page_offset;
@@ -196,7 +195,7 @@ int __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
* will then handle the error.
*/
if (ret)
- read_pages(mapping, filp, &page_pool, ret);
+ read_pages(mapping, filp, &page_pool, ret, gfp_mask);
BUG_ON(!list_empty(&page_pool));
out:
return ret;