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| author |   Barry Song <v-songbaohua@oppo.com> | 2024-08-31 08:28:23 +1200 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2024-09-09 16:39:03 -0700 |
| commit | 903edea6c53f097f5f0c847fdbbfab0c6c44f241 (patch) | |
| tree | affe2ba4fe674539dc12820768435ae4569d3e78 /include/linux/gfp_types.h | |
| parent | mm: document __GFP_NOFAIL must be blockable (diff) | |
| download | linux-rng-903edea6c53f097f5f0c847fdbbfab0c6c44f241.tar.xz linux-rng-903edea6c53f097f5f0c847fdbbfab0c6c44f241.zip | |
mm: warn about illegal __GFP_NOFAIL usage in a more appropriate location and manner
Three points for this change:
1. We should consolidate all warnings in one place. Currently, the
order > 1 warning is in the hotpath, while others are in less
likely scenarios. Moving all warnings to the slowpath will reduce
the overhead for order > 1 and increase the visibility of other
warnings.
2. We currently have two warnings for order: one for order > 1 in
the hotpath and another for order > costly_order in the laziest
path. I suggest standardizing on order > 1 since it's been in
use for a long time.
3. We don't need to check for __GFP_NOWARN in this case. __GFP_NOWARN
is meant to suppress allocation failure reports, but here we're
dealing with bug detection, not allocation failures. So replace
WARN_ON_ONCE_GFP by WARN_ON_ONCE.
[v-songbaohua@oppo.com: also update the doc for __GFP_NOFAIL with order > 1]
Link: https://lkml.kernel.org/r/20240903223935.1697-1-21cnbao@gmail.com
Link: https://lkml.kernel.org/r/20240830202823.21478-4-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: David Rientjes <rientjes@google.com>
Cc: "Eugenio Pérez" <eperezma@redhat.com>
Cc: Hailong.Liu <hailong.liu@oppo.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Xie Yongji <xieyongji@bytedance.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/gfp_types.h')
| -rw-r--r-- | include/linux/gfp_types.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h index 4a1fa7706b0c..65db9349f905 100644 --- a/include/linux/gfp_types.h +++ b/include/linux/gfp_types.h @@ -253,7 +253,8 @@ enum { * used only when there is no reasonable failure policy) but it is * definitely preferable to use the flag rather than opencode endless * loop around allocator. - * Using this flag for costly allocations is _highly_ discouraged. + * Allocating pages from the buddy with __GFP_NOFAIL and order > 1 is + * not supported. Please consider using kvmalloc() instead. */ #define __GFP_IO ((__force gfp_t)___GFP_IO) #define __GFP_FS ((__force gfp_t)___GFP_FS) |