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c07a4dab24
The checking of @c->nroot->flags and @c->dirty_[n|p]n_cnt in function
nothing_to_commit() is not atomic, which could be raced with modifying
of lpt, for example:
P1 P2 P3
run_gc
ubifs_garbage_collect
do_commit
ubifs_return_leb
ubifs_lpt_lookup_dirty
dirty_cow_nnode
do_commit
nothing_to_commit
if (test_bit(DIRTY_CNODE, &c->nroot->flags)
// false
test_and_set_bit(DIRTY_CNODE, &nnode->flags)
c->dirty_nn_cnt += 1
ubifs_assert(c, c->dirty_nn_cnt == 0)
// false !
Fetch a reproducer in Link:
UBIFS error (ubi0:0 pid 2747): ubifs_assert_failed
UBIFS assert failed: c->dirty_pn_cnt == 0, in fs/ubifs/commit.c
Call Trace:
ubifs_ro_mode+0x58/0x70 [ubifs]
ubifs_assert_failed+0x6a/0x90 [ubifs]
do_commit+0x5b7/0x930 [ubifs]
ubifs_run_commit+0xc6/0x1a0 [ubifs]
ubifs_sync_fs+0xd8/0x110 [ubifs]
sync_filesystem+0xb4/0x120
do_syscall_64+0x6f/0x140
Fix it by checking @c->dirty_[n|p]n_cnt and @c->nroot state with
@c->lp_mutex locked.
Fixes: 944fdef52c ("UBIFS: do not start the commit if there is nothing to commit")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218162
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
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
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In order to build the documentation, use ``make htmldocs`` or
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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.