| From: "Uladzislau Rezki (Sony)" <urezki@gmail.com> |
| Subject: mm: skip might_alloc() warnings when PF_MEMALLOC is set |
| Date: Tue, 7 Oct 2025 14:20:33 +0200 |
| |
| might_alloc() catches invalid blocking allocations in contexts where |
| sleeping is not allowed. |
| |
| However when PF_MEMALLOC is set, the page allocator already skips reclaim |
| and other blocking paths. In such cases, a blocking gfp_mask does not |
| actually lead to blocking, so triggering might_alloc() splats is |
| misleading. |
| |
| Adjust might_alloc() to skip warnings when the current task has |
| PF_MEMALLOC set, matching the allocator's actual blocking behaviour. |
| |
| Link: https://lkml.kernel.org/r/20251007122035.56347-9-urezki@gmail.com |
| Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> |
| Reviewed-by: Baoquan He <bhe@redhat.com> |
| Acked-by: Michal Hocko <mhocko@suse.com> |
| Cc: Alexander Potapenko <glider@google.com> |
| Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
| Cc: Marco Elver <elver@google.com> |
| Cc: Michal Hocko <mhocko@kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| include/linux/sched/mm.h | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/include/linux/sched/mm.h~mm-skip-might_alloc-warnings-when-pf_memalloc-is-set |
| +++ a/include/linux/sched/mm.h |
| @@ -318,6 +318,9 @@ static inline void might_alloc(gfp_t gfp |
| fs_reclaim_acquire(gfp_mask); |
| fs_reclaim_release(gfp_mask); |
| |
| + if (current->flags & PF_MEMALLOC) |
| + return; |
| + |
| might_sleep_if(gfpflags_allow_blocking(gfp_mask)); |
| } |
| |
| _ |
