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Sat, 28 Feb 2026 01:45:06 -0800 (PST) From: Qing Wang To: wangqing7171@gmail.com Cc: brauner@kernel.org, jack@suse.cz, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+512459401510e2a9a39f@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Subject: Re: [syzbot] [ext4?] INFO: task hung in filename_rmdir Date: Sat, 28 Feb 2026 17:44:57 +0800 Message-Id: <20260228094457.2253079-1-wangqing7171@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260228082942.1853224-1-wangqing7171@gmail.com> References: <20260228082942.1853224-1-wangqing7171@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Sat, 28 Feb 2026 at 16:29, Qing Wang wrote: > #syz test > > diff --git a/fs/namei.c b/fs/namei.c > index 58f715f7657e..34a5d49b038b 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -5383,7 +5383,7 @@ int filename_rmdir(int dfd, struct filename *name) > if (error) > goto exit2; > > - dentry = start_dirop(path.dentry, &last, lookup_flags); > + dentry = __start_dirop(path.dentry, &last, lookup_flags, TASK_KILLABLE); > error = PTR_ERR(dentry); > if (IS_ERR(dentry)) > goto exit3; Using interruptible locks [0] did not resolve the issue and it only improved reliability. [0] __start_dirop(..., TASK_KILLABLE) -> down_write_killable_nested() The root cause of this hung task may be a deadlock, and I've found a recent patchset [1] that may be related. Further analysis of this patch would be helpful. [1] ff7c4ea11a05 - VFS: add start_creating_killable() and start_removing_killable() 4037d966f034 - VFS: introduce start_dirop() and end_dirop() 5c8752729970 - VFS/nfsd/ovl: introduce start_renaming() and end_renaming() ac50950ca143 - VFS/ovl/smb: introduce start_renaming_dentry() 833d2b3a072f - Add start_renaming_two_dentries() -- Qing