[PATCH] mm: make slab and vmalloc allocators __GFP_NOLOCKDEP aware

[Michal Hocko]

sl?b and vmalloc allocators reduce the given gfp mask for their internal
needs. For that they use GFP_RECLAIM_MASK to preserve the reclaim
behavior and constrains.

__GFP_NOLOCKDEP is not a part of that mask because it doesn't really
control the reclaim behavior strictly speaking. On the other hand
it tells the underlying page allocator to disable reclaim recursion
detection so arguably it should be part of the mask.

Having __GFP_NOLOCKDEP in the mask will not alter the behavior in any
form so this change is safe pretty much by definition. It also adds
a support for this flag to SL?B and vmalloc allocators which will in
turn allow its use to kvmalloc as well. A lack of the support has been
noticed recently in http://lkml.kernel.org/r/20211119225435.GZ449541@xxxxxxxxxxxxxxxxxxx

Reported-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
 mm/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/internal.h b/mm/internal.h
index 3b79a5c9427a..2ceea20b5b2a 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -21,7 +21,7 @@
 #define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\
 			__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_NOFAIL|\
 			__GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\
-			__GFP_ATOMIC)
+			__GFP_ATOMIC|__GFP_NOLOCKDEP)
 
 /* The GFP flags allowed during early boot */
 #define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS))
-- 
2.30.2

-- 
Michal Hocko
SUSE Labs