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([2001:1a48:8:903:1ed6:4f73:ce38:f9d4]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-447b7217afesm4158791f8f.23.2026.04.29.01.28.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Apr 2026 01:28:03 -0700 (PDT) Message-ID: <2d996917-60bb-4ef9-b397-65decf3b296d@suse.com> Date: Wed, 29 Apr 2026 10:28:02 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/slab: Add kvfree_atomic() helper Content-Language: en-US To: "Uladzislau Rezki (Sony)" , Herbert Xu , linux-crypto@vger.kernel.org, "Harry Yoo (Oracle)" Cc: LKML , Andrew Morton , Hao Li References: <20260428161419.94695-1-urezki@gmail.com> From: Vlastimil Babka In-Reply-To: <20260428161419.94695-1-urezki@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit +Cc SLAB maintainers. Please use get_maintainers.pl next time. On 4/28/26 18:14, Uladzislau Rezki (Sony) wrote: > 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) Acked-by: Vlastimil Babka (SUSE) > --- > include/linux/slab.h | 3 +++ > mm/slub.c | 16 ++++++++++++++++ > 2 files changed, 19 insertions(+) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 15a60b501b95..2b5ab488e96b 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -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); > diff --git a/mm/slub.c b/mm/slub.c > index 2b2d33cc735c..b096677c8152 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -6802,6 +6802,22 @@ 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.