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b=moSNTz60+w3p/T7Zd9IShd1kdgP0RV90fFSfnL1+vsHRSeh7tj/xyJii/z3OkUe+FH5nC6 nDIO9qHEMECFFjhGZMOLkqH8yUAM0Ai8uTeYNHFA90EYfsqxqbzBhPJ+TK7a9bv0eiGMuP 81V/4OSzpxsKhGaX+yZzdQ9VeD8rJB4c17ywfQUb2sLa7sGbm6H1iJ4i7zTPzIdcG0EAD6 q6aVhSJDZeodIqNpr0c6vxMg/IC8+57UCNk1ybDfE1powYj1yG2Q1Dxrf1CCkgRkQCX7YC emBsonRLxlE+KQdqi/00x1h+EfKsFJb+q1hvEaIK9T0W8yoWtDdh2iA66ixJYw== Received: from localhost (gaia.codewreck.org [local]) by gaia.codewreck.org (OpenSMTPD) with ESMTPA id 05349875; Mon, 18 Aug 2025 21:55:29 +0000 (UTC) Date: Tue, 19 Aug 2025 06:55:13 +0900 From: Dominique Martinet To: Oleg Nesterov Cc: syzbot , David Howells , K Prateek Nayak , akpm@linux-foundation.org, brauner@kernel.org, dvyukov@google.com, elver@google.com, glider@google.com, jack@suse.cz, kasan-dev@googlegroups.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, willy@infradead.org Subject: Re: [syzbot] [fs?] [mm?] INFO: task hung in v9fs_file_fsync Message-ID: References: <20250818114404.GA18626@redhat.com> <68a31e33.050a0220.e29e5.00a6.GAE@google.com> <20250818125625.GC18626@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250818125625.GC18626@redhat.com> X-Stat-Signature: yb6t67cjj6ipzfq3zk9sscaukzujj683 X-Rspam-User: X-Rspamd-Queue-Id: D058140008 X-Rspamd-Server: rspam05 X-HE-Tag: 1755554138-825672 X-HE-Meta: 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 UNQPA+FO 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 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 Oleg, Oleg Nesterov wrote on Mon, Aug 18, 2025 at 02:56:26PM +0200: > On 08/18, syzbot wrote: > > syzbot has tested the proposed patch and the reproducer did not trigger any issue: (I hate that syzbot identified "hung in v9fs_file_fsync" but doesn't bother to Cc 9p folks... all the time..) > Dominique, David, > > Perhaps you can reconsider the fix that Prateek and I tried to propose > in this thread > > [syzbot] [netfs?] INFO: task hung in netfs_unbuffered_write_iter > https://lore.kernel.org/all/67dedd2f.050a0220.31a16b.003f.GAE@google.com/ I've re-read that thread, and I still think this must be a problem specific to syzbot doing obviously bogus things (e.g. replying before request, or whatever it is this particular repro is doing), but I guess your patch is also sane enough and the 9p optimization is probably not really needed here Please resend as a proper patch, and I'll just run some quick check (and a trivial benchmark) and pick it up Thanks, -- Dominique Martinet | Asmadeus