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After commitc0e473a0d2("block: fix race between set_blocksize and read paths") was merged, set_blocksize() called by sb_set_blocksize() now locks the inode of the backing device file. As a result of this change, syzbot started reporting deadlock warnings due to a circular dependency involving the semaphore "ns_sem" of the nilfs object, the inode lock of the backing device file, and the locks that this inode lock is transitively dependent on. This is caused by a new lock dependency added by the above change, since init_nilfs() calls sb_set_blocksize() in the lock section of "ns_sem". However, these warnings are false positives because init_nilfs() is called in the early stage of the mount operation and the filesystem has not yet started. The reason why "ns_sem" is locked in init_nilfs() was to avoid a race condition in nilfs_fill_super() caused by sharing a nilfs object among multiple filesystem instances (super block structures) in the early implementation. However, nilfs objects and super block structures have long ago become one-to-one, and there is no longer any need to use the semaphore there. So, fix this issue by removing the use of the semaphore "ns_sem" in init_nilfs(). Link: https://lkml.kernel.org/r/20250503053327.12294-1-konishi.ryusuke@gmail.com Fixes:c0e473a0d2("block: fix race between set_blocksize and read paths") Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> Reported-by: syzbot+00f7f5b884b117ee6773@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=00f7f5b884b117ee6773 Tested-by: syzbot+00f7f5b884b117ee6773@syzkaller.appspotmail.com Reported-by: syzbot+f30591e72bfc24d4715b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f30591e72bfc24d4715b Tested-by: syzbot+f30591e72bfc24d4715b@syzkaller.appspotmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.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 reStructuredText 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.