From: Yi Chen chenyi77@huawei.com
[ Upstream commit 594b6d0428ae304e0b44457398beb458b938f005 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/segment.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index c2866561263e..9010c3d9715e 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -186,7 +186,10 @@ void f2fs_register_inmem_page(struct inode *inode, struct page *page) { struct inmem_pages *new;
- f2fs_set_page_private(page, ATOMIC_WRITTEN_PAGE); + if (PagePrivate(page)) + set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE); + else + f2fs_set_page_private(page, ATOMIC_WRITTEN_PAGE);
new = f2fs_kmem_cache_alloc(inmem_entry_slab, GFP_NOFS);