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Linux kernel source tree
6125b201cc
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
pc : f2fs_put_page+0x1c/0x26c
lr : __revoke_inmem_pages+0x544/0x75c
f2fs_put_page+0x1c/0x26c
__revoke_inmem_pages+0x544/0x75c
__f2fs_commit_inmem_pages+0x364/0x3c0
f2fs_commit_inmem_pages+0xc8/0x1a0
f2fs_ioc_commit_atomic_write+0xa4/0x15c
f2fs_ioctl+0x5b0/0x1574
file_ioctl+0x154/0x320
do_vfs_ioctl+0x164/0x740
__arm64_sys_ioctl+0x78/0xa4
el0_svc_common+0xbc/0x1d0
el0_svc_handler+0x74/0x98
el0_svc+0x8/0xc
In f2fs_put_page, we access page->mapping is NULL.
The root cause is:
In some cases, the page refcount and ATOMIC_WRITTEN_PAGE
flag miss set for page-priavte flag has been set.
We add f2fs_bug_on like this:
f2fs_register_inmem_page()
{
...
f2fs_set_page_private(page, ATOMIC_WRITTEN_PAGE);
f2fs_bug_on(F2FS_I_SB(inode), !IS_ATOMIC_WRITTEN_PAGE(page));
...
}
The bug on stack follow link this:
PC is at f2fs_register_inmem_page+0x238/0x2b4
LR is at f2fs_register_inmem_page+0x2a8/0x2b4
f2fs_register_inmem_page+0x238/0x2b4
f2fs_set_data_page_dirty+0x104/0x164
set_page_dirty+0x78/0xc8
f2fs_write_end+0x1b4/0x444
generic_perform_write+0x144/0x1cc
__generic_file_write_iter+0xc4/0x174
f2fs_file_write_iter+0x2c0/0x350
__vfs_write+0x104/0x134
vfs_write+0xe8/0x19c
SyS_pwrite64+0x78/0xb8
To fix this issue, let's add page refcount add page-priavte flag.
The page-private flag is not cleared and needs further analysis.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Ge Qiu <qiuge@huawei.com>
Signed-off-by: Dehe Gu <gudehe@huawei.com>
Signed-off-by: Yi Chen <chenyi77@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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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.