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Received: from willy by casper.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1x0L6v-0000000GhcR-3ihs; Sat, 29 Aug 2026 15:36:49 +0000 Date: Sat, 29 Aug 2026 16:36:49 +0100 From: Matthew Wilcox To: Guilherme Giacomo Simoes Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+395b7abe9696862fc188@syzkaller.appspotmail.com Subject: Re: [PATCH] mm: fix the race on huge alloc failed Message-ID: References: <20260829100034.423064-1-trintaeoitogc@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260829100034.423064-1-trintaeoitogc@gmail.com> X-Stat-Signature: snar985ehjtmjay13rymo71b839qghbg X-Rspamd-Queue-Id: C5A5316000B X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1788017813-316412 X-HE-Meta: U2FsdGVkX1/JPwTXqeW+IemvyyYuHebZeMliWWWpU7Iy65b1lgy5L6eN42nOOHRPn2wnF5xzZQk428wT1MhsBmVq/JcU6D4lzP5vqLPcx4RzbPXnyY9aZyh3b/lnBE9Tj9fmXuuJQUNZyxipSU7T5uMr17WjRBjzZVSbUEfFdRPQcjOPC1G2T+LzSmMR5SknpRta/zqDCXAkaHkFJH/PqE2xwFQ+YhgmpFLvm3t38MZDpo+V0syTNIEn9Zm7kqDIGimSNfmDIGP8V0ujfV846QuGSqvqO/NP2yPoizPZWoMNpN9L+nFHtbP/5ldSucopiojGQunwPpIaCMR3q0RrnQC3nB03NiZGVq+drAUngtAF2dBEA7z+cErv6GmiMukaDOcj4Uk/aiTgE3fg5semefk7JUHBsoddh+Mo978swBndiyfbxs9wTB6ej56kb79CMHWHQfCgHQYp7DOwtVfX+OIoTkqneWn2h6u6YDmJmDJN/qK8p1eUu1MsgBL7hIhY90Goo4GUpeOPwi0Bd0YlvtJDFu2Cha9Hxcf4awZj/8yNeVKGoIN4J2Cv74UiPhCeMZt0fDZZ1qOmWEcp/tWcvC2bp5apF31sV3F8RBqWIMCQcOEpLTgOVMrTtwjgzjck7R0O4HdDZjWL5+kP8Ew8mDn95BS3V9bVEHobTg4o+Yl3lhgf5lLqjRM4Ndk0CFjd8PbseCw2y+/yW+APNPK9lTFkPhsybKAr6II2UzOnB7+gwonFvSbcYfS1GlYYA3AByIILSRJjPhexjA/3i6rzb/bJVHV9U1J/RDbeobNCLc8mmt3wT3gfjYXZFgvm1avewkf2N3PPMF2rj2bbZ0zwlZOhslMban7g5k72f6RjgL746+k4+M4paQhZBnMK1/MC7EFTz7dkPJjX/Jv5iKcan53UocR5iEKtxBgVcjMcaHg8YzqWATuSigk4JOKn4hAsDw9L7PJoQ7/cAsEmUh/ R7m64lDV X2gdHmzMY1d1LjMycN0XpwXONj0nK/GsYyGUZ1SA+YJotkdVlHu4JAYsEmgwqYJw28Iq0Hki4ZSDQAwGoT1rQnMJ7qEIaKXXEWOFW3E0iFfu75haTW9XfH4o91A1+N4v8dOLjmkB+GqtXN4Pj6ouacxw68VZ/o7syGjtfVWCCXiLwu2qHOJG/bXSTkBlpovvujYn8BxhDJ1gePXJkvKBtDftl4FZ1VE8F2pYsa5wcN427YXQXTTZd2swtZXDtPTfjsz+vNWNYdE/eXZX29whkXi/iAUTVcjlfAcTu6Fdclfwgmrn2RnPHqbRFqnYJ/b9NXtNsEqEbWgCnAWqlUctJXuHVgvAbDU5jM44QvCNqNx8NvYVPMnD9+m6dOiBzSYw50T7SOgCDQGSN7Plc+5P8RgCZ1Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Aug 29, 2026 at 07:00:34AM -0300, Guilherme Giacomo Simoes wrote: > The race occurs because the reader (__vmf_anon_prepare()) checks > `vma->anon->vma` without holding the mmap_lock and withou the > READ_ONCE() macro. Since the writer (__anon_vma_prepare()) is holding the > mmap_lock and updating the pointer, it creates a data race as the two > access are not properly synchronized. also this explanation is bogus. i don't have time to fix it right now.