As Dinosaur Huang reported, there is a potential deadlock in between
GC and mkwrite():
Thread A Thread B
- do_page_mkwrite
- f2fs_vm_page_mkwrite
- lock_page
- f2fs_balance_fs
- mutex_lock(gc_mutex)
- f2fs_gc
- do_garbage_collect
- ra_data_block
- grab_cache_page
- f2fs_balance_fs
- mutex_lock(gc_mutex)
In order to fix this, we just move f2fs_balance_fs() out of page lock's
coverage in f2fs_vm_page_mkwrite().
Reported-by: Dinosaur Huang <dinosaur.hu...@unisoc.com>
Signed-off-by: Chao Yu <yuch...@huawei.com>
---
fs/f2fs/file.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index c0560d62dbee..ed3290225506 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -67,6 +67,8 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
f2fs_bug_on(sbi, f2fs_has_inline_data(inode));
+ f2fs_balance_fs(sbi, true);
+
file_update_time(vmf->vma->vm_file);
down_read(&F2FS_I(inode)->i_mmap_sem);
lock_page(page);
@@ -120,8 +122,6 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
out_sem:
up_read(&F2FS_I(inode)->i_mmap_sem);
- f2fs_balance_fs(sbi, dn.node_changed);
-
sb_end_pagefault(inode->i_sb);
err:
return block_page_mkwrite_return(err);
--
2.18.0.rc1
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