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mm/slab: Add kvfree_atomic() helper

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kvmalloc() now supports non-sleeping GFP flags, including
the vmalloc fallback path. This means it may return vmalloc
memory even for GFP_ATOMIC and GFP_NOWAIT allocations.

Freeing such memory with kvfree() may then end up calling
vfree(), which is not safe for non-sleeping contexts.

Introduce kvfree_atomic() helper for such cases. It mirrors
kvfree(), but uses vfree_atomic() for vmalloced memory.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: Harry Yoo (Oracle) <harry@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Uladzislau Rezki (Sony) 2026-04-28 18:14:18 +02:00 committed by Herbert Xu
parent 09ae540e1d
commit dad0d91cc2
2 changed files with 19 additions and 0 deletions
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3
include/linux/slab.h
View File

@ -1234,6 +1234,9 @@ void *kvrealloc_node_align_noprof(const void *p, size_t size, unsigned long alig
extern void kvfree(const void *addr);
DEFINE_FREE(kvfree, void *, if (!IS_ERR_OR_NULL(_T)) kvfree(_T))
extern void kvfree_atomic(const void *addr);
DEFINE_FREE(kvfree_atomic, void *, if (!IS_ERR_OR_NULL(_T)) kvfree_atomic(_T))
extern void kvfree_sensitive(const void *addr, size_t len);
unsigned int kmem_cache_size(struct kmem_cache *s);

16
mm/slub.c
View File

@ -6882,6 +6882,22 @@ void kvfree(const void *addr)
}
EXPORT_SYMBOL(kvfree);
/**
* kvfree_atomic() - Free memory.
* @addr: Pointer to allocated memory.
*
* Same as kvfree(), but uses vfree_atomic() for vmalloc
* backed memory. Must not be called from NMI context.
*/
void kvfree_atomic(const void *addr)
{
if (is_vmalloc_addr(addr))
vfree_atomic(addr);
else
kfree(addr);
}
EXPORT_SYMBOL(kvfree_atomic);
/**
* kvfree_sensitive - Free a data object containing sensitive information.
* @addr: address of the data object to be freed.