145cd3e36e
[ Upstream commit 0f28be64d132aaf95d06375c8002ad9ecea69d71 ] Lockdep reported the following issue when mounting erofs with a domain_id: ============================================ WARNING: possible recursive locking detected 6.8.0-rc7-xfstests #521 Not tainted -------------------------------------------- mount/396 is trying to acquire lock: ffff907a8aaaa0e0 (&type->s_umount_key#50/1){+.+.}-{3:3}, at: alloc_super+0xe3/0x3d0 but task is already holding lock: ffff907a8aaa90e0 (&type->s_umount_key#50/1){+.+.}-{3:3}, at: alloc_super+0xe3/0x3d0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&type->s_umount_key#50/1); lock(&type->s_umount_key#50/1); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by mount/396: #0: ffff907a8aaa90e0 (&type->s_umount_key#50/1){+.+.}-{3:3}, at: alloc_super+0xe3/0x3d0 #1: ffffffffc00e6f28 (erofs_domain_list_lock){+.+.}-{3:3}, at: erofs_fscache_register_fs+0x3d/0x270 [erofs] stack backtrace: CPU: 1 PID: 396 Comm: mount Not tainted 6.8.0-rc7-xfstests #521 Call Trace: <TASK> dump_stack_lvl+0x64/0xb0 validate_chain+0x5c4/0xa00 __lock_acquire+0x6a9/0xd50 lock_acquire+0xcd/0x2b0 down_write_nested+0x45/0xd0 alloc_super+0xe3/0x3d0 sget_fc+0x62/0x2f0 vfs_get_super+0x21/0x90 vfs_get_tree+0x2c/0xf0 fc_mount+0x12/0x40 vfs_kern_mount.part.0+0x75/0x90 kern_mount+0x24/0x40 erofs_fscache_register_fs+0x1ef/0x270 [erofs] erofs_fc_fill_super+0x213/0x380 [erofs] This is because the file_system_type of both erofs and the pseudo-mount point of domain_id is erofs_fs_type, so two successive calls to alloc_super() are considered to be using the same lock and trigger the warning above. Therefore add a nodev file_system_type called erofs_anon_fs_type in fscache.c to silence this complaint. Because kern_mount() takes a pointer to struct file_system_type, not its (string) name. So we don't need to call register_filesystem(). In addition, call init_pseudo() in erofs_anon_init_fs_context() as suggested by Al Viro, so that we can remove erofs_fc_fill_pseudo_super(), erofs_fc_anon_get_tree(), and erofs_anon_context_ops. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Fixes: a9849560c55e ("erofs: introduce a pseudo mnt to manage shared cookies") Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-and-tested-by: Jingbo Xu <jefflexu@linux.alibaba.com> Reviewed-by: Yang Erkun <yangerkun@huawei.com> Link: https://lore.kernel.org/r/20240307101018.2021925-1-libaokun1@huawei.com Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> 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.