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Mon, 06 Oct 2025 23:32:31 -0700 (PDT) Received: from [192.168.50.136] ([118.32.98.101]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-28e8d110cdfsm153463955ad.13.2025.10.06.23.32.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Oct 2025 23:32:31 -0700 (PDT) Message-ID: <3b66d603-543d-4616-92a5-9e6e32f116be@kzalloc.com> Date: Tue, 7 Oct 2025 15:32:27 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] mm/migrate: make sure folio_unlock() before folio_wait_writeback() To: Byungchul Park , Hillf Danton Cc: David Hildenbrand , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel_team@skhynix.com, Yeoreum Yun References: <20251002081612.53281-1-byungchul@sk.com> <20251002220211.8009-1-hdanton@sina.com> <20251003004828.GA75385@system.software.com> <20251003005230.GB75385@system.software.com> Content-Language: en-US From: Yunseong Kim Organization: kzalloc In-Reply-To: <20251003005230.GB75385@system.software.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: ragcmem9z5385k1r1spqrrecf16a1xjy X-Rspamd-Queue-Id: D1008100006 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1759818752-740606 X-HE-Meta: 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 Al9B3US+ lJ+MfqOPAq3oMLiyty+3J67wU+WBPkMGK5HGf8MOJCCh/GmO7yfqEABPn6/emmCKLS6MmyDwI7AXtR6Ad3XNNXd6/tFyFSpPr/fM6kN8RIL+NL6g0T6bt5foxyKtSGZjybmSuvDT1vNl2maH40IzfpKHFd628JT2a8LfOTSfsadSvPeUEQ5hXzuALmA251RIkMgcePlalJjxIC5D0XI9yl+u/l/0TtexPDAFzF8FINIRBYfA4CUzHOtFNqAygfZyxd+HTLUu4+7hfFoH2Yw2KRZEXuyplUaYQ353xSqGs215zJkXhlC9agp5kN4RA2DXu+t9cwiP/f2cE0mDq9XSELubbnquN7qnZfVN910AlKXFCVqW5FbFST/vKEx8i0TGZLAkNidhlV5C0cntge9yYJKE0CPxeDVNTbn5JR2Iu4Eq+9LlgQ37bjWzGp9rpYCIsef4NLpnIi6qRC53KRCCoK+T6icQNxqTZ3kD1zGjHUGmW98k= 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: Hi Hillf, Here are the syzlang and kernel log, and you can also find the gist snippet in the body of the first RFC mail: https://gist.github.com/kzall0c/a6091bb2fd536865ca9aabfd017a1fc5 I am reviewing this issue again on the v6.17, The issue is always reproducible, usually occurring within about 10k attempts with the 8 procs. On 10/3/25 9:52 AM, Byungchul Park wrote: > On Fri, Oct 03, 2025 at 09:48:28AM +0900, Byungchul Park wrote: >> On Fri, Oct 03, 2025 at 06:02:10AM +0800, Hillf Danton wrote: >>> On Thu, 2 Oct 2025 13:38:59 +0200 David Hildenbrand wrote: >>>> >>>> If it's a real issue, I wonder if a trylock on the writeback path could >>>> be an option. >>>> >>> Given Thanks to Yunseong for reporting the issue, testing, and confirming if >>> this patch can resolve the issue, could you share your reproducer with >>> reviewers Byungchul? >> >> Sure. Yunseong told me it's 100% reproducable. Yunseong, can you help >> him reproduce the issue, please? > > +to ysk@kzalloc.com > >> >> Byungchul > Thank you! Yunseong