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([2600:1700:6476:1430:4935:3bd4:e0b7:fd95]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-672d9089322sm2428882d50.21.2026.09.24.11.20.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Sep 2026 11:20:44 -0700 (PDT) Message-ID: Subject: Re: [PATCH] nilfs2: fix deadlock between nilfs_evict_inode() and find_inode() From: Viacheslav Dubeyko To: Ryusuke Konishi Cc: linux-nilfs , LKML , syzbot+6646318bbcf419411bc5@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com Date: Thu, 24 Sep 2026 11:20:41 -0700 In-Reply-To: <20260923164345.18456-1-konishi.ryusuke@gmail.com> References: <20260923164345.18456-1-konishi.ryusuke@gmail.com> Autocrypt: addr=slava@dubeyko.com; prefer-encrypt=mutual; keydata=mQINBGgaTLYBEADaJc/WqWTeunGetXyyGJ5Za7b23M/ozuDCWCp+yWUa2GqQKH40dxRIR zshgOmAue7t9RQJU9lxZ4ZHWbi1Hzz85+0omefEdAKFmxTO6+CYV0g/sapU0wPJws3sC2Pbda9/eJ ZcvScAX2n/PlhpTnzJKf3JkHh3nM1ACO3jzSe2/muSQJvqMLG2D71ccekr1RyUh8V+OZdrPtfkDam V6GOT6IvyE+d+55fzmo20nJKecvbyvdikWwZvjjCENsG9qOf3TcCJ9DDYwjyYe1To8b+mQM9nHcxp jUsUuH074BhISFwt99/htZdSgp4csiGeXr8f9BEotRB6+kjMBHaiJ6B7BIlDmlffyR4f3oR/5hxgy dvIxMocqyc03xVyM6tA4ZrshKkwDgZIFEKkx37ec22ZJczNwGywKQW2TGXUTZVbdooiG4tXbRBLxe ga/NTZ52ZdEkSxAUGw/l0y0InTtdDIWvfUT+WXtQcEPRBE6HHhoeFehLzWL/o7w5Hog+0hXhNjqte fzKpI2fWmYzoIb6ueNmE/8sP9fWXo6Av9m8B5hRvF/hVWfEysr/2LSqN+xjt9NEbg8WNRMLy/Y0MS p5fgf9pmGF78waFiBvgZIQNuQnHrM+0BmYOhR0JKoHjt7r5wLyNiKFc8b7xXndyCDYfniO3ljbr0j tXWRGxx4to6FwARAQABtCZWaWFjaGVzbGF2IER1YmV5a28gPHNsYXZhQGR1YmV5a28uY29tPokCVw QTAQoAQQIbAQUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBFXDC2tnzsoLQtrbBDlc2cL fhEB1BQJoGl5PAhkBAAoJEDlc2cLfhEB17DsP/jy/Dx19MtxWOniPqpQf2s65enkDZuMIQ94jSg7B F2qTKIbNR9SmsczjyjC+/J7m7WZRmcqnwFYMOyNfh12aF2WhjT7p5xEAbvfGVYwUpUrg/lcacdT0D Yk61GGc5ZB89OAWHLr0FJjI54bd7kn7E/JRQF4dqNsxU8qcPXQ0wLHxTHUPZu/w5Zu/cO+lQ3H0Pj pSEGaTAh+tBYGSvQ4YPYBcV8+qjTxzeNwkw4ARza8EjTwWKP2jWAfA/ay4VobRfqNQ2zLoo84qDtN Uxe0zPE2wobIXELWkbuW/6hoQFPpMlJWz+mbvVms57NAA1HO8F5c1SLFaJ6dN0AQbxrHi45/cQXla 9hSEOJjxcEnJG/ZmcomYHFneM9K1p1K6HcGajiY2BFWkVet9vuHygkLWXVYZ0lr1paLFR52S7T+cf 6dkxOqu1ZiRegvFoyzBUzlLh/elgp3tWUfG2VmJD3lGpB3m5ZhwQ3rFpK8A7cKzgKjwPp61Me0o9z HX53THoG+QG+o0nnIKK7M8+coToTSyznYoq9C3eKeM/J97x9+h9tbizaeUQvWzQOgG8myUJ5u5Dr4 6tv9KXrOJy0iy/dcyreMYV5lwODaFfOeA4Lbnn5vRn9OjuMg1PFhCi3yMI4lA4umXFw0V2/OI5rgW BQELhfvW6mxkihkl6KLZX8m1zcHitCpWaWFjaGVzbGF2IER1YmV5a28gPFNsYXZhLkR1YmV5a29Aa WJtLmNvbT6JAlQEEwEKAD4WIQRVwwtrZ87KC0La2wQ5XNnC34RAdQUCaBpd7AIbAQUJA8JnAAULCQ gHAgYVCgkICwIEFgIDAQIeAQIXgAAKCRA5XNnC34RAdYjFEACiWBEybMt1xjRbEgaZ3UP5i2bSway DwYDvgWW5EbRP7JcqOcZ2vkJwrK3gsqC3FKpjOPh7ecE0I4vrabH1Qobe2N8B2Y396z24mGnkTBbb 16Uz3PC93nFN1BA0wuOjlr1/oOTy5gBY563vybhnXPfSEUcXRd28jI7z8tRyzXh2tL8ZLdv1u4vQ8 E0O7lVJ55p9yGxbwgb5vXU4T2irqRKLxRvU80rZIXoEM7zLf5r7RaRxgwjTKdu6rYMUOfoyEQQZTD 4Xg9YE/X8pZzcbYFs4IlscyK6cXU0pjwr2ssjearOLLDJ7ygvfOiOuCZL+6zHRunLwq2JH/RmwuLV mWWSbgosZD6c5+wu6DxV15y7zZaR3NFPOR5ErpCFUorKzBO1nA4dwOAbNym9OGkhRgLAyxwpea0V0 ZlStfp0kfVaSZYo7PXd8Bbtyjali0niBjPpEVZdgtVUpBlPr97jBYZ+L5GF3hd6WJFbEYgj+5Af7C UjbX9DHweGQ/tdXWRnJHRzorxzjOS3003ddRnPtQDDN3Z/XzdAZwQAs0RqqXrTeeJrLppFUbAP+HZ TyOLVJcAAlVQROoq8PbM3ZKIaOygjj6Yw0emJi1D9OsN2UKjoe4W185vamFWX4Ba41jmCPrYJWAWH fAMjjkInIPg7RLGs8FiwxfcpkILP0YbVWHiNAabQoVmlhY2hlc2xhdiBEdWJleWtvIDx2ZHViZXlr b0BrZXJuZWwub3JnPokCVAQTAQoAPhYhBFXDC2tnzsoLQtrbBDlc2cLfhEB1BQJoVemuAhsBBQkDw mcABQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAAoJEDlc2cLfhEB1GRwP/1scX5HO9Sk7dRicLD/fxo ipwEs+UbeA0/TM8OQfdRI4C/tFBYbQCR7lD05dfq8VsYLEyrgeLqP/iRhabLky8LTaEdwoAqPDc/O 9HRffx/faJZqkKc1dZryjqS6b8NExhKOVWmDqN357+Cl/H4hT9wnvjCj1YEqXIxSd/2Pc8+yw/KRC AP7jtRzXHcc/49Lpz/NU5irScusxy2GLKa5o/13jFK3F1fWX1wsOJF8NlTx3rLtBy4GWHITwkBmu8 zI4qcJGp7eudI0l4xmIKKQWanEhVdzBm5UnfyLIa7gQ2T48UbxJlWnMhLxMPrxgtC4Kos1G3zovEy Ep+fJN7D1pwN9aR36jVKvRsX7V4leIDWGzCdfw1FGWkMUfrRwgIl6i3wgqcCP6r9YSWVQYXdmwdMu 1RFLC44iF9340S0hw9+30yGP8TWwd1mm8V/+zsdDAFAoAwisi5QLLkQnEsJSgLzJ9daAsE8KjMthv hUWHdpiUSjyCpigT+KPl9YunZhyrC1jZXERCDPCQVYgaPt+Xbhdjcem/ykv8UVIDAGVXjuk4OW8la nf8SP+uxkTTDKcPHOa5rYRaeNj7T/NClRSd4z6aV3F6pKEJnEGvv/DFMXtSHlbylhyiGKN2Amd0b4 9jg+DW85oNN7q2UYzYuPwkHsFFq5iyF1QggiwYYTpoVXsw Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (by Flathub.org) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2026-09-24 at 01:41 +0900, Ryusuke Konishi wrote: > Syzbot reported a deadlock between nilfs_evict_inode(), executed via > an asynchronous workqueue (kworker) as: >=20 > =C2=A0 process_one_work() > =C2=A0=C2=A0=C2=A0 process_scheduled_works() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nilfs_iput_work_func() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nilfs_dispose_list() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 iput() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 iput_f= inal() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 evict() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 s_op->evict_inode() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nilfs_evict_inode() >=20 > and find_inode(), called via >=20 > =C2=A0 nilfs_mkdir() > =C2=A0=C2=A0=C2=A0 nilfs_new_inode() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nilfs_insert_inode_locked() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 insert_inode_locked4() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 inode_insert5() > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 find_i= node() >=20 > When an inode is deleted (i_nlink =3D=3D 0), nilfs_evict_inode() clears > its > ifile bitmap entry and then synchronously triggers the log writer via > nilfs_transaction_commit() if IS_SYNC(inode) is true. >=20 > If a concurrent directory creation via nilfs_new_inode() attempts to > allocate the same newly freed inode number, however, find_inode() > called > just before inserting it into the inode hash, blocks waiting for the > old > inode's evict() to complete. >=20 > Meanwhile, the synchronous log writer invoked from > nilfs_evict_inode() > tries to acquire a write lock on 'ns_segctor_sem' which is read > locked > by the caller of nilfs_new_inode() (in this case, nilfs_mkdir()), > resulting in a deadlock. >=20 > The synchronous log writer invocation from nilfs_evict_inode() is a > legacy artifact; it is no longer necessary because the call itself > (triggered by iput()) is now handled asynchronously with a kworker > if i_nlink =3D=3D 0.=C2=A0 It merely increases the risk of deadlock. >=20 > Fix this deadlock by removing the synchronous log writer trigger from > nilfs_evict_inode(). >=20 > Reported-by: syzbot+6646318bbcf419411bc5@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=3D6646318bbcf419411bc5 > Fixes: 7ef3ff2fea8b ("nilfs2: fix deadlock of segment constructor > over I_SYNC flag") > Tested-by: syzbot+6646318bbcf419411bc5@syzkaller.appspotmail.com > Cc: stable@vger.kernel.org > Signed-off-by: Ryusuke Konishi > --- > Hi Viacheslav, >=20 > Please apply this bug fix. >=20 > This fixes a deadlock issue that had been reported by syzbot but > remained unresolved for over a year. >=20 > Thanks, > Ryusuke Konishi >=20 > =C2=A0fs/nilfs2/inode.c | 6 ------ > =C2=A01 file changed, 6 deletions(-) >=20 > diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c > index 64437aed8390..33490e8063eb 100644 > --- a/fs/nilfs2/inode.c > +++ b/fs/nilfs2/inode.c > @@ -895,13 +895,7 @@ void nilfs_evict_inode(struct inode *inode) > =C2=A0 > =C2=A0 nilfs_clear_inode(inode); > =C2=A0 > - if (IS_SYNC(inode)) > - nilfs_set_transaction_flag(NILFS_TI_SYNC); > =C2=A0 nilfs_transaction_commit(sb); > - /* > - * May construct a logical segment and may fail in sync > mode. > - * But delete_inode has no return value. > - */ > =C2=A0} > =C2=A0 > =C2=A0int nilfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, Applied. Thanks, Slava.