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[209.85.167.53]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-2f79d302a57sm15054081fa.43.2024.09.18.20.03.40 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Sep 2024 20:03:40 -0700 (PDT) Received: by mail-lf1-f53.google.com with SMTP id 2adb3069b0e04-536584f6c84so458045e87.0 for ; Wed, 18 Sep 2024 20:03:40 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCXbwFYrli9kenU7G3fAyforIpjJUN8MF2yE7n8liqmkORvUN8EBopmH1BwPvZP+wK2rSmKMi35GJw==@kvack.org X-Received: by 2002:a05:6512:220d:b0:535:6a75:8ac8 with SMTP id 2adb3069b0e04-53678fc24e6mr13825268e87.23.1726715020071; Wed, 18 Sep 2024 20:03:40 -0700 (PDT) MIME-Version: 1.0 References: <74cceb67-2e71-455f-a4d4-6c5185ef775b@meta.com> <52d45d22-e108-400e-a63f-f50ef1a0ae1a@meta.com> <5bee194c-9cd3-47e7-919b-9f352441f855@kernel.dk> <459beb1c-defd-4836-952c-589203b7005c@meta.com> In-Reply-To: From: Linus Torvalds Date: Thu, 19 Sep 2024 05:03:23 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Known and unfixed active data loss bug in MM + XFS with large folios since Dec 2021 (any kernel from 6.1 upwards) To: Dave Chinner Cc: Matthew Wilcox , Chris Mason , Jens Axboe , Christian Theune , linux-mm@kvack.org, "linux-xfs@vger.kernel.org" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Dao , regressions@lists.linux.dev, regressions@leemhuis.info Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Queue-Id: 1FBE5A0004 X-Rspamd-Server: rspam01 X-Stat-Signature: uouefysunmyouuief8fmma5yt8p5dw6u X-HE-Tag: 1726715024-420471 X-HE-Meta: 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 Mhcj1HHb qDFN3E7YL9A/dMU8ykBJJIWu1oJOxzp5Rb8QpJ+WN4WVYn3bpDtCkEBBw5fckWwPcHgJO25ikd0+YOfVVzNA+Tb7mTSh3n4WJamdEN88gQBJsjbHwW3bhvCaBkWSVPhMLgQyRD2v0cdAYcprAtSvddVPFTq2SwZzMGHAFsVolQ6Mi3LaQSzsTCi7yqXdVkUZOWe4gFcxgJiQlBUCYBrR+jTZNwgvrZxHlSbKRyRPzJjo/XyvH2pbZ8wVc6cjP/+SBHRSIxmrMC3Cu64ZLFuY/6RzipzF3Ae+9tyrHxn7GV7q0FD/4DSFUzdW5pCI33KmBsi8+2IUKNin0J5+A0t0fDhswBkaL1zZD9EVx+59DWMnhl2wADmu9venJugSWKnUWJdtE7sjQoN8qqC19w3ID2qjAeNcAIAJc6E+pozARvg0QYnZGredJNoms2yUmVGr0az78y8Rd/n6xU35cbQow1/dbSUHhnj9l5xd8vTKFZnd+h+Ysaa1L2KurkvAAAq6CisVfNui/VPScAmAzpFbqdQn6T+z1vi5GtGiSAnNop6cy7jNwsgErz6nTagNriKKHQnQ0H4WhndxQFf0DOrNzONMu3wk5lQtc3pj0d3PUAbiq3bg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000016, 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 Thu, 19 Sept 2024 at 03:43, Dave Chinner wrote: > > Should we be asking for 6758c1128ceb to be backported to all > stable kernels then? I think we should just do the simple one-liner of adding a "xas_reset()" to after doing xas_split_alloc() (or do it inside the xas_split_alloc()). That said, I do also think it would be really good if the 'xa_lock*()' family of functions also had something like a WARN_ON_ONCE(xas->xa_node && !xa_err(xas->xa_node)); which I think would have caught this. Because right now nothing at all checks "we dropped the xa lock, and held xas state over it". Linus