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a=rsa-sha256; c=relaxed/relaxed; d=pankajraghav.com; s=MBO0001; t=1725288527; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eRC1BvtLT2vA0iVXzms3Z2oYXmmRg/cLCIDrpDyKuD4=; b=sRtSVxXzSTx8suCqivUdxTopF/qs1vmlknYQADnE84cSnOnEJYkK00HoUqTznXGpFAEX3Y GBgpQzpVhLl/C0CVJCDwczLrIPFKWjMdOcSVZu0aV4EzKBf+/ykcc+nOXiERk3xsBeksQF Y2XMVd+wsqFqAc3B2tO67Ovgi6C6W2P3IRDrI34vwdUnfPcIlxKluzzEB/AfTk3OvZyU1z ck/3+kej41HeK4F/PTnOpxSs4raty8q0tnmMFvpBm66sl4h7CnUuPfV3EA4YevhUnZGl1r IBRtiDnsbP/OCyK2IQyCcHxZ/oZV3F4cYjJnnXolEyekVAgPwbbdGcZOFm9hhA== Date: Mon, 2 Sep 2024 14:48:41 +0000 From: "Pankaj Raghav (Samsung)" To: Christian Brauner Cc: Matthew Wilcox , sfr@canb.auug.org.au, akpm@linux-foundation.org, linux-next@vger.kernel.org, mcgrof@kernel.org, ziy@nvidia.com, da.gomez@samsung.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Pankaj Raghav , Sven Schnelle Subject: Re: [PATCH] mm: don't convert the page to folio before splitting in split_huge_page() Message-ID: <20240902144841.gfk4bakvtz6bxdqx@quentin> References: <20240902124931.506061-2-kernel@pankajraghav.com> <20240902-wovor-knurren-01ba56e0460e@brauner> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240902-wovor-knurren-01ba56e0460e@brauner> X-Stat-Signature: i74b47shzacijtz1cw7bx5cfbw13fd89 X-Rspamd-Queue-Id: 76A6080015 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1725288532-274864 X-HE-Meta: U2FsdGVkX19BrWLxU2Q6hBUpo3aqB9BGjtaJj1bRDmo3zUH1jh+LS8NEsesIcaiwDFEuVtcdAcaa+0ap1TydkemhF+M5X8V+1acWLKEgbfHL5V+LKJvkI0Ko2DyAJux60eLUF4Px9pRIH//IphjgvelDm35yN7PKGIN5ppnmnKtCqf0aotSgrYl+S7WGBPOsUTZoi+Rqouw0XcNwhGhw/OMyQNydR9Ly5u11XaqVeqM2OCOxc9CDoYdfzjECwwxjUOYPeKpjJGOpadzl43qPYFsrDTsctApfRWetq37VfJQLSev8GUdVoCTlGxDFjAGRuBRJNUqc8feob9vYt2WDQV5ecpmO7Kjde2bdsY13BOB3v+8qCD6xp8rXqBS7YXYbnl5A17lKH48z2tiDc0JcITJmhi7FXRElyaem7/l1iF/r5iiwXnxplxEWX14HfEedFFBIfPm2CvqW2xzUXMdlauI1Lz4nGy9AbwfpGWQev1eaM1hRX0/WFHFrP4xsURkChxbXzhtrQtpfwoWT6qldnUKym3sMb7Z0PCNkG+mNtWKKlEZlG76ezXwIhO0JzWlMpdT5Uiv4f0DpDasLeO8G3FmgFCjHnveTJwdQg+ripCfbB0Xuev/DE3wprt1qHZiibva4olqAzJ4le4QO1QD9QkAoZl74D5yhg5zj/XnFN+RoCFghQK6nnnjWslyQDQQ/Pcbm5JUioqFtkhUHwbf5tPxsuqjgEwBDDo/UzAwbKs7GLw3yQYGpayNx/SjEx56bmkSSrkzyYJyH+KaSnLPG52dSyxfRc4PsRTA2mwhbhIr1ahCfSJCNY3oUA5a0YiI5OZld4kcfPN/J40VVhJJDRgOtkUTbrk6dMOeL2Ai6IWhcMQgygtbqFOQic3m78ZQa8Ii/z/yXhcJqv0gyHJPm7Jn5zmXvGohg0Z4rFFdwmT13OEm29KflesTcpnLVZo6nb2vRRax7oGAs/9FXOy7 qDV3E3Ym IgmW+z4F9mglXnIhqxVQbAmrFWJBH30/fhUkQPBS83LdBQMNdpEZUtCh4T8N1wCbwoN46GXAa7xnkvKEpICvWsAL2acNcho1K3xVqa+Na+gyCkYH0m4GdDbEtNjkVE3elXsjSMWmvLfIWxyNqhK60yWw4B+9sZvFtXilFalE/D0AslpmjNj2e3KKtU6R6yOuJUKNJEH+LgwWcFhJOa9GT9uyD5EtbnDg7Nt21WzVLBkPets5/lN0YwwxL3gic+0oPzy9Dm9m1kk5TfWBpF+w47IuzRf7O8edL3UdGE+6LRQ7RqrOz7fgJjm/l1EjEcq2XsdurS7z+lFIHCdNDxixpU0qU4g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 Mon, Sep 02, 2024 at 04:21:09PM +0200, Christian Brauner wrote: > On Mon, Sep 02, 2024 at 03:00:37PM GMT, Matthew Wilcox wrote: > > On Mon, Sep 02, 2024 at 02:49:32PM +0200, Pankaj Raghav (Samsung) wrote: > > > From: Pankaj Raghav > > > > > > Sven reported that a commit from bs > ps series was breaking the ksm ltp > > > test[1]. > > > > > > split_huge_page() takes precisely a page that is locked, and it also > > > expects the folio that contains that page to be locked after that > > > huge page has been split. The changes introduced converted the page to > > > folio, and passed the head page to be split, which might not be locked, > > > resulting in a kernel panic. > > > > > > This commit fixes it by always passing the correct page to be split from > > > split_huge_page() with the appropriate minimum order for splitting. > > > > This should be folded into the patch that is broken, not be a separate > > fix commit, otherwise it introduces a bisection hazard which are to be > > avoided when possible. > > Patch folded into "mm: split a folio in minimum folio order chunks" > with the Link to this patch. Please double-check. Thanks a lot! I still don't see it upstream[1]. Maybe it is yet to be pushed? [1] https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/commit/?h=vfs.blocksize&id=fd031210c9ceb399db1dea001c6a5e98f3b4e2e7