A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-29 19:21:31 -04:00
Code Issues Projects Releases Packages Wiki Activity

mm, memcg: use consistent gfp flags during readahead

Browse source 
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.

[[email protected]: coding-style fixes]
[[email protected]: restrict gfp mask in mpage_alloc]
  Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Steve French <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Mike Marshall <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Changman Lee <[email protected]>
Cc: Chao Yu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Michal Hocko 2016-07-26 15:24:53 -07:00 • committed by Linus Torvalds
commit 8a5c743e30
8 changed files with 19 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

4
fs/mpage.c
View file

@ -71,6 +71,8 @@ mpage_alloc(struct block_device *bdev,
{
struct bio *bio;
/* Restrict the given (page cache) mask for slab allocations */
gfp_flags &= GFP_KERNEL;
bio = bio_alloc(gfp_flags, nr_vecs);
if (bio == NULL && (current->flags & PF_MEMALLOC)) {
@ -362,7 +364,7 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
sector_t last_block_in_bio = 0;
struct buffer_head map_bh;
unsigned long first_logical_block = 0;
gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
gfp_t gfp = readahead_gfp_mask(mapping);
map_bh.b_state = 0;
map_bh.b_size = 0;