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[ Upstream commit5eaac835f2] There is a potential deadlock reported by syzbot as below: F2FS-fs (loop2): invalid crc value F2FS-fs (loop2): Found nat_bits in checkpoint F2FS-fs (loop2): Mounted with checkpoint version = 48b305e4 ====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0 Not tainted ------------------------------------------------------ syz-executor.2/32123 is trying to acquire lock: ffff0000c0e1a608 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0x54/0xb4 mm/memory.c:5644 but task is already holding lock: ffff0001317c6088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2205 [inline] ffff0001317c6088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_ioc_get_encryption_pwsalt fs/f2fs/file.c:2334 [inline] ffff0001317c6088 (&sbi->sb_lock){++++}-{3:3}, at: __f2fs_ioctl+0x1370/0x3318 fs/f2fs/file.c:4151 which lock already depends on the new lock. Chain exists of: &mm->mmap_lock --> &nm_i->nat_tree_lock --> &sbi->sb_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sbi->sb_lock); lock(&nm_i->nat_tree_lock); lock(&sbi->sb_lock); lock(&mm->mmap_lock); Let's try to avoid above deadlock condition by moving __might_fault() out of sbi->sb_lock coverage. Fixes:95fa90c9e5("f2fs: support recording errors into superblock") Link: https://lore.kernel.org/linux-f2fs-devel/000000000000cd5fe305ef617fe2@google.com/T/#u Reported-by: syzbot+4793f6096d174c90b4f7@syzkaller.appspotmail.com Signed-off-by: Chao Yu <chao@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.