From: Barry Song <v-songbaohua@xxxxxxxx> -v3: * collect reviewed-by, acked-by etc. Michal, Christoph, Vlastimil, Davidlohr, thanks! * use Jason's patch[1] to fix vdpa and refine his changelog. * refine changelogs [1] https://lore.kernel.org/all/20240808054320.10017-1-jasowang@xxxxxxxxxx/ -v2: https://lore.kernel.org/linux-mm/20240731000155.109583-1-21cnbao@xxxxxxxxx/ * adjust vpda fix according to Jason and Michal's feedback, I would expect Jason to test it, thanks! * split BUG_ON of unavoidable failure and the case GFP_ATOMIC | __GFP_NOFAIL into two patches according to Vlastimil and Michal. * collect Michal's acked-by for patch 2 - the doc; * remove the new GFP_NOFAIL from this series, that one would be a separate enhancement patchset later on. -v1: https://lore.kernel.org/linux-mm/20240724085544.299090-1-21cnbao@xxxxxxxxx/ __GFP_NOFAIL carries the semantics of never failing, so its callers do not check the return value: %__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller cannot handle allocation failures. The allocation could block indefinitely but will never return with failure. Testing for failure is pointless. However, __GFP_NOFAIL can sometimes fail if it exceeds size limits or is used with GFP_ATOMIC/GFP_NOWAIT in a non-sleepable context. This can expose security vulnerabilities due to potential NULL dereferences. Since __GFP_NOFAIL does not support non-blocking allocation, we introduce GFP_NOFAIL with inclusive blocking semantics and encourage using GFP_NOFAIL as a replacement for __GFP_NOFAIL in non-mm. If we must still fail a nofail allocation, we should trigger a BUG rather than exposing NULL dereferences to callers who do not check the return value. * The discussion started from this topic: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL https://lore.kernel.org/linux-mm/20240717230025.77361-1-21cnbao@xxxxxxxxx/ Thank you to Michal, Christoph, Vlastimil, and Hailong for all the comments. Barry Song (3): mm: document __GFP_NOFAIL must be blockable mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails mm: prohibit NULL deference exposed for unsupported non-blockable __GFP_NOFAIL Jason Wang (1): vduse: avoid using __GFP_NOFAIL drivers/vdpa/vdpa_user/iova_domain.c | 19 +++++++++++-------- drivers/vdpa/vdpa_user/iova_domain.h | 1 + include/linux/gfp_types.h | 5 ++++- include/linux/slab.h | 4 +++- mm/page_alloc.c | 14 ++++++++------ mm/util.c | 1 + 6 files changed, 28 insertions(+), 16 deletions(-) -- 2.39.3 (Apple Git-146)
