diff options
| author | Hao Ge <hao.ge@linux.dev> | 2026-09-23 14:37:59 +0800 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-09-25 17:30:39 +0200 |
| commit | b78b728e21c32ec4c330b299f657fb1eb02dffc2 (patch) | |
| tree | febfa1c4b03d0eb2681391b77fe45fe64b16a2f8 /include/linux | |
| parent | 35d442ed1f86465e49df3119fb898f985186db13 (diff) | |
netfs: Fix missing alloc tagging of direct mempool allocations
Commit 1d78d56c43ef ("netfs: Fix folio_queue ENOMEM in writeback by
adding a mempool") added a mempool for the folio_queues and made the
request, subrequest and folio_queue allocations distinguish between
writeback and everything else. Writeback is part of memory reclaim
and must not fail due to ENOMEM, so it allocates under GFP_NOFS
through mempool_alloc(), which may dip into the pool's reserve and,
if that runs empty, wait for elements to be returned. The
GFP_KERNEL paths, which can return -ENOMEM to their callers, invoke
the pool's ->alloc() callback directly instead.
The direct call, however, skips the alloc_hooks() wrapper that the
mempool_alloc() macro provides. The pool callbacks, mempool_alloc_slab()
and mempool_kmalloc(), call kmem_cache_alloc_noprof() and kmalloc_noprof()
and rely on current->alloc_tag having been set by the caller. With
CONFIG_MEM_ALLOC_PROFILING_DEBUG=y this leads to
current->alloc_tag not set
WARNING: ./include/linux/alloc_tag.h:161 at __alloc_tagging_slab_alloc_hook
alloc_tag was not set
WARNING: ./include/linux/alloc_tag.h:166 at __alloc_tagging_slab_free_hook
at allocation and free time respectively, as reported when reading
files on a CIFS mount. The allocations are also missing from
/proc/allocinfo.
Wrap the direct ->alloc() invocations in alloc_hooks() with a new
mempool_alloc_noreserve() helper in include/linux/mempool.h, next to
the other alloc_hooks()-wrapped macros such as mempool_alloc(). The
GFP_KERNEL paths keep their failable allocation semantics, they just
get tagged now.
Fixes: 1d78d56c43ef ("netfs: Fix folio_queue ENOMEM in writeback by adding a mempool")
Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Closes: https://lore.kernel.org/all/0b004319-9ef7-437c-a4dd-174d6a9a83db@mailbox.org/
Tested-by: Erhard Furtner <erhard_f@mailbox.org>
Suggested-by: Suren Baghdasaryan <surenb@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Hao Ge <hao.ge@linux.dev>
Link: https://patch.msgid.link/20260923063759.34667-1-hao.ge@linux.dev
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mempool.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/mempool.h b/include/linux/mempool.h index a0fa6d43e0dc..6da502aef2f7 100644 --- a/include/linux/mempool.h +++ b/include/linux/mempool.h @@ -70,6 +70,13 @@ int mempool_alloc_bulk_noprof(struct mempool *pool, void **elem, #define mempool_alloc_bulk(...) \ alloc_hooks(mempool_alloc_bulk_noprof(__VA_ARGS__)) +/* + * Allocate a new element without dipping into the pool's reserves or + * waiting. Returns NULL on failure. + */ +#define mempool_alloc_noreserve(_pool, _gfp) \ + alloc_hooks((_pool)->alloc(_gfp, (_pool)->pool_data)) + void *mempool_alloc_preallocated(struct mempool *pool) __malloc; void mempool_free(void *element, struct mempool *pool); unsigned int mempool_free_bulk(struct mempool *pool, void **elem, |