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Fri, 18 Aug 2023 19:05:22 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id 21-20020a170902c11500b001bc930d4517sm2436747pli.42.2023.08.18.19.05.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Aug 2023 19:05:21 -0700 (PDT) Sender: Guenter Roeck Date: Fri, 18 Aug 2023 19:05:20 -0700 From: Guenter Roeck To: Jaegeuk Kim Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, syzbot+e5600587fa9cbf8e3826@syzkaller.appspotmail.com Subject: Re: [f2fs-dev] [PATCH] f2fs: avoid false alarm of circular locking Message-ID: <30da1d43-d15d-4f8e-a36f-73428328d91c@roeck-us.net> References: <20230819003012.3473675-1-jaegeuk@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230819003012.3473675-1-jaegeuk@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 18, 2023 at 05:30:12PM -0700, Jaegeuk Kim wrote: > ====================================================== > WARNING: possible circular locking dependency detected > 6.5.0-rc5-syzkaller-00353-gae545c3283dc #0 Not tainted > ------------------------------------------------------ > syz-executor273/5027 is trying to acquire lock: > ffff888077fe1fb0 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2133 [inline] > ffff888077fe1fb0 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_add_inline_entry+0x300/0x6f0 fs/f2fs/inline.c:644 > > but task is already holding lock: > ffff888077fe07c8 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2108 [inline] > ffff888077fe07c8 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_add_dentry+0x92/0x230 fs/f2fs/dir.c:783 > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: > > -> #1 (&fi->i_xattr_sem){.+.+}-{3:3}: > down_read+0x9c/0x470 kernel/locking/rwsem.c:1520 > f2fs_down_read fs/f2fs/f2fs.h:2108 [inline] > f2fs_getxattr+0xb1e/0x12c0 fs/f2fs/xattr.c:532 > __f2fs_get_acl+0x5a/0x900 fs/f2fs/acl.c:179 > f2fs_acl_create fs/f2fs/acl.c:377 [inline] > f2fs_init_acl+0x15c/0xb30 fs/f2fs/acl.c:420 > f2fs_init_inode_metadata+0x159/0x1290 fs/f2fs/dir.c:558 > f2fs_add_regular_entry+0x79e/0xb90 fs/f2fs/dir.c:740 > f2fs_add_dentry+0x1de/0x230 fs/f2fs/dir.c:788 > f2fs_do_add_link+0x190/0x280 fs/f2fs/dir.c:827 > f2fs_add_link fs/f2fs/f2fs.h:3554 [inline] > f2fs_mkdir+0x377/0x620 fs/f2fs/namei.c:781 > vfs_mkdir+0x532/0x7e0 fs/namei.c:4117 > do_mkdirat+0x2a9/0x330 fs/namei.c:4140 > __do_sys_mkdir fs/namei.c:4160 [inline] > __se_sys_mkdir fs/namei.c:4158 [inline] > __x64_sys_mkdir+0xf2/0x140 fs/namei.c:4158 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > -> #0 (&fi->i_sem){+.+.}-{3:3}: > check_prev_add kernel/locking/lockdep.c:3142 [inline] > check_prevs_add kernel/locking/lockdep.c:3261 [inline] > validate_chain kernel/locking/lockdep.c:3876 [inline] > __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5144 > lock_acquire kernel/locking/lockdep.c:5761 [inline] > lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5726 > down_write+0x93/0x200 kernel/locking/rwsem.c:1573 > f2fs_down_write fs/f2fs/f2fs.h:2133 [inline] > f2fs_add_inline_entry+0x300/0x6f0 fs/f2fs/inline.c:644 > f2fs_add_dentry+0xa6/0x230 fs/f2fs/dir.c:784 > f2fs_do_add_link+0x190/0x280 fs/f2fs/dir.c:827 > f2fs_add_link fs/f2fs/f2fs.h:3554 [inline] > f2fs_mkdir+0x377/0x620 fs/f2fs/namei.c:781 > vfs_mkdir+0x532/0x7e0 fs/namei.c:4117 > ovl_do_mkdir fs/overlayfs/overlayfs.h:196 [inline] > ovl_mkdir_real+0xb5/0x370 fs/overlayfs/dir.c:146 > ovl_workdir_create+0x3de/0x820 fs/overlayfs/super.c:309 > ovl_make_workdir fs/overlayfs/super.c:711 [inline] > ovl_get_workdir fs/overlayfs/super.c:864 [inline] > ovl_fill_super+0xdab/0x6180 fs/overlayfs/super.c:1400 > vfs_get_super+0xf9/0x290 fs/super.c:1152 > vfs_get_tree+0x88/0x350 fs/super.c:1519 > do_new_mount fs/namespace.c:3335 [inline] > path_mount+0x1492/0x1ed0 fs/namespace.c:3662 > do_mount fs/namespace.c:3675 [inline] > __do_sys_mount fs/namespace.c:3884 [inline] > __se_sys_mount fs/namespace.c:3861 [inline] > __x64_sys_mount+0x293/0x310 fs/namespace.c:3861 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > rlock(&fi->i_xattr_sem); > lock(&fi->i_sem); > lock(&fi->i_xattr_sem); > lock(&fi->i_sem); > > Reported-and-tested-by: syzbot+e5600587fa9cbf8e3826@syzkaller.appspotmail.com > Fixes: 5eda1ad1aaff "f2fs: fix deadlock in i_xattr_sem and inode page lock" > Signed-off-by: Jaegeuk Kim Tested-by: Guenter Roeck > --- > fs/f2fs/f2fs.h | 24 +++++++++++++++--------- > fs/f2fs/inline.c | 3 ++- > 2 files changed, 17 insertions(+), 10 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index c602ff2403b6..c0b7417f1d87 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -2122,15 +2122,6 @@ static inline int f2fs_down_read_trylock(struct f2fs_rwsem *sem) > return down_read_trylock(&sem->internal_rwsem); > } > > -#ifdef CONFIG_DEBUG_LOCK_ALLOC > -static inline void f2fs_down_read_nested(struct f2fs_rwsem *sem, int subclass) > -{ > - down_read_nested(&sem->internal_rwsem, subclass); > -} > -#else > -#define f2fs_down_read_nested(sem, subclass) f2fs_down_read(sem) > -#endif > - > static inline void f2fs_up_read(struct f2fs_rwsem *sem) > { > up_read(&sem->internal_rwsem); > @@ -2141,6 +2132,21 @@ static inline void f2fs_down_write(struct f2fs_rwsem *sem) > down_write(&sem->internal_rwsem); > } > > +#ifdef CONFIG_DEBUG_LOCK_ALLOC > +static inline void f2fs_down_read_nested(struct f2fs_rwsem *sem, int subclass) > +{ > + down_read_nested(&sem->internal_rwsem, subclass); > +} > + > +static inline void f2fs_down_write_nested(struct f2fs_rwsem *sem, int subclass) > +{ > + down_write_nested(&sem->internal_rwsem, subclass); > +} > +#else > +#define f2fs_down_read_nested(sem, subclass) f2fs_down_read(sem) > +#define f2fs_down_write_nested(sem, subclass) f2fs_down_write(sem) > +#endif > + > static inline int f2fs_down_write_trylock(struct f2fs_rwsem *sem) > { > return down_write_trylock(&sem->internal_rwsem); > diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c > index 4638fee16a91..0d185ad5e469 100644 > --- a/fs/f2fs/inline.c > +++ b/fs/f2fs/inline.c > @@ -641,7 +641,8 @@ int f2fs_add_inline_entry(struct inode *dir, const struct f2fs_filename *fname, > } > > if (inode) { > - f2fs_down_write(&F2FS_I(inode)->i_sem); > + f2fs_down_write_nested(&F2FS_I(inode)->i_sem, > + SINGLE_DEPTH_NESTING); > page = f2fs_init_inode_metadata(inode, dir, fname, ipage); > if (IS_ERR(page)) { > err = PTR_ERR(page); > -- > 2.42.0.rc1.204.g551eb34607-goog > > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel