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Tue, 01 Sep 2026 04:53:03 -0700 (PDT) From: Guilherme Giacomo Simoes To: ljs@kernel.org Cc: akpm@linux-foundation.org, david@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, liam@infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, pfalcato@suse.de, riel@surriel.com, rppt@kernel.org, surenb@google.com, syzbot+395b7abe9696862fc188@syzkaller.appspotmail.com, trintaeoitogc@gmail.com, vbabka@kernel.org, willy@infradead.org Subject: Re: [PATCH] mm: fix the race on huge alloc failed Date: Tue, 1 Sep 2026 08:52:48 -0300 Message-ID: <20260901115248.26650-1-trintaeoitogc@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit First, thanks Lorenzo to help me with this... "Lorenzo Stoakes (ARM)" wrote: > > > > I don't think it's enough to just add a data_race() to this one read of > > > > vma->anon_vma. I think it's quite prevalent. There's probably other > > > > syzbot reports that mention it. > > > > It sounds to me like the most cromulent solution is simply adding a > > > > /* maybe vma_has_anon? */ > > static inline bool vma_has_anon_vma(const struct vm_area_struct *vma) > > { > > return data_race(vma->anon_vma); > > } > > > > and churn everything to use it. > > I'd prefer vma_is_faulted(). That'll align better with my scalable CoW work > also. > > Anyway I agree with Pedro that a data_race() resolution is appropriate here > rather than an unnecessary READ_ONCE()/WRITE_ONCE() pair. Okay, if only a data_race(...) is enough to silently KCSAN, I can send a new PATCH or send a v2 of this PATCH with this new implementation and with a fix of commit message