[PATCH 2/2] mm: introduce PF_MEMALLOC_NOWARN

[Kent Overstreet <kent.overstreet@linux.dev>]

If we're using PF_MEMALLOC, we might have a fallback and might not to
warn about a failing allocation - thus we need a PF_* equivalent of
__GFP_NOWARN.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
---
 include/linux/sched.h    | 8 ++++----
 include/linux/sched/mm.h | 8 +++++++-
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index cdb8ea53c365..36a5046ea3fa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1632,11 +1632,11 @@ extern struct pid *cad_pid;
 #define PF_KSWAPD		0x00020000	/* I am kswapd */
 #define PF_MEMALLOC_NOFS	0x00040000	/* All allocation requests will inherit GFP_NOFS */
 #define PF_MEMALLOC_NOIO	0x00080000	/* All allocation requests will inherit GFP_NOIO */
-#define PF_LOCAL_THROTTLE	0x00100000	/* Throttle writes only against the bdi I write to,
+#define PF_MEMALLOC_NOWARN	0x00100000	/* All allocation requests will inherit __GFP_NOWARN */
+#define PF_LOCAL_THROTTLE	0x00200000	/* Throttle writes only against the bdi I write to,
 						 * I am cleaning dirty pages from some other bdi. */
-#define PF_KTHREAD		0x00200000	/* I am a kernel thread */
-#define PF_RANDOMIZE		0x00400000	/* Randomize virtual address space */
-#define PF__HOLE__00800000	0x00800000
+#define PF_KTHREAD		0x00400000	/* I am a kernel thread */
+#define PF_RANDOMIZE		0x00800000	/* Randomize virtual address space */
 #define PF__HOLE__01000000	0x01000000
 #define PF__HOLE__02000000	0x02000000
 #define PF_NO_SETAFFINITY	0x04000000	/* Userland is not allowed to meddle with cpus_mask */
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index f00d7ecc2adf..817f5c1bf3d5 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -236,7 +236,10 @@ static inline gfp_t current_gfp_context(gfp_t flags)
 {
 	unsigned int pflags = READ_ONCE(current->flags);
 
-	if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_PIN))) {
+	if (unlikely(pflags & (PF_MEMALLOC_NOIO |
+			       PF_MEMALLOC_NOFS |
+			       PF_MEMALLOC_NOWARN |
+			       PF_MEMALLOC_PIN))) {
 		/*
 		 * NOIO implies both NOIO and NOFS and it is a weaker context
 		 * so always make sure it makes precedence
@@ -246,6 +249,9 @@ static inline gfp_t current_gfp_context(gfp_t flags)
 		else if (pflags & PF_MEMALLOC_NOFS)
 			flags &= ~__GFP_FS;
 
+		if (pflags & PF_MEMALLOC_NOWARN)
+			flags |= __GFP_NOWARN;
+
 		if (pflags & PF_MEMALLOC_PIN)
 			flags &= ~__GFP_MOVABLE;
 	}
-- 
2.43.0