[PATCH 1/2] xfs: Add __GFP_NORETRY and __GFP_NOWARN to open-coded __GFP_NOFAIL allocations

[Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>]

kmem_alloc(), kmem_zone_alloc() and xfs_buf_allocate_memory() are doing
open-coded __GFP_NOFAIL allocations with warning messages as a canary.
But since small !__GFP_NOFAIL allocations retry forever inside memory
allocator unless TIF_MEMDIE is set, the canary does not help even if
allocations are stalling. Thus, this patch adds __GFP_NORETRY so that
we can know possibility of allocation deadlock.

If a patchset which makes small !__GFP_NOFAIL !__GFP_FS allocations not
retry inside memory allocator is merged, warning messages by
warn_alloc_failed() will dominate warning messages by the canary
because each thread calls warn_alloc_failed() for approximately
every 2 milliseconds. Thus, this patch also adds __GFP_NOWARN so that
we won't flood kernel logs by these open-coded __GFP_NOFAIL allocations.
Next patch compensates for lack of comm name and pid by addding them to
the canary.

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
---
 fs/xfs/kmem.c    | 4 ++--
 fs/xfs/xfs_buf.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
index a7a3a63..1fcf90d 100644
--- a/fs/xfs/kmem.c
+++ b/fs/xfs/kmem.c
@@ -46,7 +46,7 @@ void *
 kmem_alloc(size_t size, xfs_km_flags_t flags)
 {
        int     retries = 0;
-       gfp_t   lflags = kmem_flags_convert(flags);
+       gfp_t   lflags = kmem_flags_convert(flags) | __GFP_NORETRY | 
__GFP_NOWARN;
        void    *ptr;
 
        do {
@@ -111,7 +111,7 @@ void *
 kmem_zone_alloc(kmem_zone_t *zone, xfs_km_flags_t flags)
 {
        int     retries = 0;
-       gfp_t   lflags = kmem_flags_convert(flags);
+       gfp_t   lflags = kmem_flags_convert(flags) | __GFP_NORETRY | 
__GFP_NOWARN;
        void    *ptr;
 
        do {
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 8ecffb3..cbd4f91 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -289,7 +289,7 @@ xfs_buf_allocate_memory(
 {
        size_t                  size;
        size_t                  nbytes, offset;
-       gfp_t                   gfp_mask = xb_to_gfp(flags);
+       gfp_t                   gfp_mask = xb_to_gfp(flags) | __GFP_NORETRY | 
__GFP_NOWARN;
        unsigned short          page_count, i;
        xfs_off_t               start, end;
        int                     error;
-- 
1.8.3.1