This is a note to let you know that I've just added the patch titled
f2fs: compress: fix potential deadlock
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
f2fs-compress-fix-potential-deadlock.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a4c0253c6fd4d0c2e1b0323dd1ec7d3e68ad22a5
Author: Chao Yu <chao@xxxxxxxxxx>
Date: Mon Jan 11 17:42:53 2021 +0800
f2fs: compress: fix potential deadlock
[ Upstream commit 3afae09ffea5e08f523823be99a784675995d6bb ]
generic/269 reports a hangtask issue, the root cause is ABBA deadlock
described as below:
Thread A Thread B
- down_write(&sbi->gc_lock) -- A
- f2fs_write_data_pages
- lock all pages in cluster -- B
- f2fs_write_multi_pages
- f2fs_write_raw_pages
- f2fs_write_single_data_page
- f2fs_balance_fs
- down_write(&sbi->gc_lock) -- A
- f2fs_gc
- do_garbage_collect
- ra_data_block
- pagecache_get_page -- B
To fix this, it needs to avoid calling f2fs_balance_fs() if there is
still cluster pages been locked in context of cluster writeback, so
instead, let's call f2fs_balance_fs() in the end of
f2fs_write_raw_pages() when all cluster pages were unlocked.
Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 4bcbacfe33259..7a774c9e4cb89 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1415,7 +1415,7 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted,
NULL, NULL, wbc, io_type,
- compr_blocks);
+ compr_blocks, false);
if (ret) {
if (ret == AOP_WRITEPAGE_ACTIVATE) {
unlock_page(cc->rpages[i]);
@@ -1450,6 +1450,9 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
*submitted += _submitted;
}
+
+ f2fs_balance_fs(F2FS_M_SB(mapping), true);
+
return 0;
out_err:
for (++i; i < cc->cluster_size; i++) {
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index aa34d620bec98..d72c99d9bd1f4 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2743,7 +2743,8 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
sector_t *last_block,
struct writeback_control *wbc,
enum iostat_type io_type,
- int compr_blocks)
+ int compr_blocks,
+ bool allow_balance)
{
struct inode *inode = page->mapping->host;
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
@@ -2881,7 +2882,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
}
unlock_page(page);
if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode) &&
- !F2FS_I(inode)->cp_task)
+ !F2FS_I(inode)->cp_task && allow_balance)
f2fs_balance_fs(sbi, need_balance_fs);
if (unlikely(f2fs_cp_error(sbi))) {
@@ -2928,7 +2929,7 @@ static int f2fs_write_data_page(struct page *page,
#endif
return f2fs_write_single_data_page(page, NULL, NULL, NULL,
- wbc, FS_DATA_IO, 0);
+ wbc, FS_DATA_IO, 0, true);
}
/*
@@ -3096,7 +3097,8 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
}
#endif
ret = f2fs_write_single_data_page(page, &submitted,
- &bio, &last_block, wbc, io_type, 0);
+ &bio, &last_block, wbc, io_type,
+ 0, true);
if (ret == AOP_WRITEPAGE_ACTIVATE)
unlock_page(page);
#ifdef CONFIG_F2FS_FS_COMPRESSION
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index bb11759191dcc..1578402c58444 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3469,7 +3469,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
struct bio **bio, sector_t *last_block,
struct writeback_control *wbc,
enum iostat_type io_type,
- int compr_blocks);
+ int compr_blocks, bool allow_balance);
void f2fs_invalidate_page(struct page *page, unsigned int offset,
unsigned int length);
int f2fs_release_page(struct page *page, gfp_t wait);
