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[90.233.213.186]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-2ef0fcfebc0sm15995001fa.102.2024.07.23.08.54.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Jul 2024 08:54:31 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 23 Jul 2024 17:54:28 +0200 To: Christoph Hellwig Cc: Uladzislau Rezki , Danilo Krummrich , cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, kees@kernel.org, ojeda@kernel.org, wedsonaf@gmail.com, mhocko@kernel.org, mpe@ellerman.id.au, chandan.babu@oracle.com, christian.koenig@amd.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org Subject: Re: [PATCH 1/2] mm: vmalloc: implement vrealloc() Message-ID: References: <20240717222427.2211-1-dakr@kernel.org> <20240717222427.2211-2-dakr@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8CBD0100004 X-Stat-Signature: 651hh5ecqeadqdjqpkjkzpn5ymsfq7w5 X-Rspam-User: X-HE-Tag: 1721750074-854086 X-HE-Meta: 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 D/Bq5CiO v4puXTgS122jZOjDjafCFFFU1GBHScIzZzeONOIKISFcB13F1nXGl9nYN444uj3gRRR7zpxf2FYlJr7ybumvxLgcO78DRw4/W0FSLZHQqhoIMu0DDetfIwMcUe4UnnXh0sp39xkNr7AMhNcX3arOON3Tg7+5MhoC8q2sjSY8eutUYFnEt3X+3S772QWc0Cycve2lSSN+0dVrOrTS38fMZaR74zg5PkWNG7NslmkA4JlNCheurbUyuXUNfvVvaIquoymigyrBaNsRjmXVTQg5a3IkZNO6WZ5IzFd1lVRdJfNCVJbADirYi1jhBHG4rv97TNKaOrAOuZUiZfNIWabWCnfHDyewJt1RFzFglq8CCCpaLaOU/3zIB49yJ/s9MpeDzgZKxRh+xbIpkAjoHCBXYOX4ga27OuvCxw1EcWoOGidtwUl1kcHKPwF1EFYpMPUjtVXeK X-Bogosity: Ham, tests=bogofilter, spamicity=0.082137, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jul 23, 2024 at 06:44:56AM -0700, Christoph Hellwig wrote: > On Tue, Jul 23, 2024 at 01:28:32PM +0200, Uladzislau Rezki wrote: > > Concurrent vfree() will lead to use-after-free. Either add a comment > > that a user is responsible for not using vrealloc()/vfree() on the same > > pointer concurrently or use find_unlink_vmap_area() which might be more > > complex when it comes to design of the vrealloc(). > > You can never use *free concurrently with *realloc. I guess it doesn't > hurt to clearly document that, but other than that we should not try > to cater to that use pattern at all. > Agree, i mentioned that as a first option. I think, it is enough to document that. Thanks! -- Uladzislau Rezki