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authorJunxiao Bi <junxiao.bi@oracle.com>2014-10-09 15:28:23 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-10-30 09:43:14 -0700
commitba572a5ae63d8b8c9e5511951eb0061f55372f7b (patch)
treef42b21cf2c1da1506b1bcd8049b920739fca0299 /include
parent25984b38a506bdcc3e2db5c0c9794868c778b5c3 (diff)
downloadlinux-linaro-stable-ba572a5ae63d8b8c9e5511951eb0061f55372f7b.tar.gz
mm: clear __GFP_FS when PF_MEMALLOC_NOIO is set
commit 934f3072c17cc8886f4c043b47eeeb1b12f8de33 upstream. commit 21caf2fc1931 ("mm: teach mm by current context info to not do I/O during memory allocation") introduces PF_MEMALLOC_NOIO flag to avoid doing I/O inside memory allocation, __GFP_IO is cleared when this flag is set, but __GFP_FS implies __GFP_IO, it should also be cleared. Or it may still run into I/O, like in superblock shrinker. And this will make the kernel run into the deadlock case described in that commit. See Dave Chinner's comment about io in superblock shrinker: Filesystem shrinkers do indeed perform IO from the superblock shrinker and have for years. Even clean inodes can require IO before they can be freed - e.g. on an orphan list, need truncation of post-eof blocks, need to wait for ordered operations to complete before it can be freed, etc. IOWs, Ext4, btrfs and XFS all can issue and/or block on arbitrary amounts of IO in the superblock shrinker context. XFS, in particular, has been doing transactions and IO from the VFS inode cache shrinker since it was first introduced.... Fix this by clearing __GFP_FS in memalloc_noio_flags(), this function has masked all the gfp_mask that will be passed into fs for the processes setting PF_MEMALLOC_NOIO in the direct reclaim path. v1 thread at: https://lkml.org/lkml/2014/9/3/32 Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: joyce.xue <xuejiufei@huawei.com> Cc: Ming Lei <ming.lei@canonical.com> Cc: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b867a4dab38a..2b1d9e974382 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1934,11 +1934,13 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
#define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
#define used_math() tsk_used_math(current)
-/* __GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags */
+/* __GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags
+ * __GFP_FS is also cleared as it implies __GFP_IO.
+ */
static inline gfp_t memalloc_noio_flags(gfp_t flags)
{
if (unlikely(current->flags & PF_MEMALLOC_NOIO))
- flags &= ~__GFP_IO;
+ flags &= ~(__GFP_IO | __GFP_FS);
return flags;
}