lkml.org 
[lkml]   [2020]   [Apr]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 5.6 010/129] f2fs: fix the panic in do_checkpoint()
    Date
    From: Sahitya Tummala <stummala@codeaurora.org>

    [ Upstream commit bf22c3cc8ce71454dddd772284773306a68031d8 ]

    There could be a scenario where f2fs_sync_meta_pages() will not
    ensure that all F2FS_DIRTY_META pages are submitted for IO. Thus,
    resulting in the below panic in do_checkpoint() -

    f2fs_bug_on(sbi, get_pages(sbi, F2FS_DIRTY_META) &&
    !f2fs_cp_error(sbi));

    This can happen in a low-memory condition, where shrinker could
    also be doing the writepage operation (stack shown below)
    at the same time when checkpoint is running on another core.

    schedule
    down_write
    f2fs_submit_page_write -> by this time, this page in page cache is tagged
    as PAGECACHE_TAG_WRITEBACK and PAGECACHE_TAG_DIRTY
    is cleared, due to which f2fs_sync_meta_pages()
    cannot sync this page in do_checkpoint() path.
    f2fs_do_write_meta_page
    __f2fs_write_meta_page
    f2fs_write_meta_page
    shrink_page_list
    shrink_inactive_list
    shrink_node_memcg
    shrink_node
    kswapd

    Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
    Reviewed-by: Chao Yu <yuchao0@huawei.com>
    Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/f2fs/checkpoint.c | 16 +++++++---------
    fs/f2fs/f2fs.h | 2 +-
    fs/f2fs/super.c | 2 +-
    3 files changed, 9 insertions(+), 11 deletions(-)

    diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
    index 44e84ac5c9411..9c88fb3d255a2 100644
    --- a/fs/f2fs/checkpoint.c
    +++ b/fs/f2fs/checkpoint.c
    @@ -1250,20 +1250,20 @@ static void unblock_operations(struct f2fs_sb_info *sbi)
    f2fs_unlock_all(sbi);
    }

    -void f2fs_wait_on_all_pages_writeback(struct f2fs_sb_info *sbi)
    +void f2fs_wait_on_all_pages(struct f2fs_sb_info *sbi, int type)
    {
    DEFINE_WAIT(wait);

    for (;;) {
    prepare_to_wait(&sbi->cp_wait, &wait, TASK_UNINTERRUPTIBLE);

    - if (!get_pages(sbi, F2FS_WB_CP_DATA))
    + if (!get_pages(sbi, type))
    break;

    if (unlikely(f2fs_cp_error(sbi)))
    break;

    - io_schedule_timeout(5*HZ);
    + io_schedule_timeout(HZ/50);
    }
    finish_wait(&sbi->cp_wait, &wait);
    }
    @@ -1384,8 +1384,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)

    /* Flush all the NAT/SIT pages */
    f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
    - f2fs_bug_on(sbi, get_pages(sbi, F2FS_DIRTY_META) &&
    - !f2fs_cp_error(sbi));

    /*
    * modify checkpoint
    @@ -1493,11 +1491,11 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)

    /* Here, we have one bio having CP pack except cp pack 2 page */
    f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
    - f2fs_bug_on(sbi, get_pages(sbi, F2FS_DIRTY_META) &&
    - !f2fs_cp_error(sbi));
    + /* Wait for all dirty meta pages to be submitted for IO */
    + f2fs_wait_on_all_pages(sbi, F2FS_DIRTY_META);

    /* wait for previous submitted meta pages writeback */
    - f2fs_wait_on_all_pages_writeback(sbi);
    + f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);

    /* flush all device cache */
    err = f2fs_flush_device_cache(sbi);
    @@ -1506,7 +1504,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)

    /* barrier and flush checkpoint cp pack 2 page if it can */
    commit_checkpoint(sbi, ckpt, start_blk);
    - f2fs_wait_on_all_pages_writeback(sbi);
    + f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);

    /*
    * invalidate intermediate page cache borrowed from meta inode which are
    diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
    index 5355be6b6755c..d39f5de114208 100644
    --- a/fs/f2fs/f2fs.h
    +++ b/fs/f2fs/f2fs.h
    @@ -3308,7 +3308,7 @@ int f2fs_get_valid_checkpoint(struct f2fs_sb_info *sbi);
    void f2fs_update_dirty_page(struct inode *inode, struct page *page);
    void f2fs_remove_dirty_inode(struct inode *inode);
    int f2fs_sync_dirty_inodes(struct f2fs_sb_info *sbi, enum inode_type type);
    -void f2fs_wait_on_all_pages_writeback(struct f2fs_sb_info *sbi);
    +void f2fs_wait_on_all_pages(struct f2fs_sb_info *sbi, int type);
    int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc);
    void f2fs_init_ino_entry_info(struct f2fs_sb_info *sbi);
    int __init f2fs_create_checkpoint_caches(void);
    diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
    index 65a7a432dfee2..686f5402660ed 100644
    --- a/fs/f2fs/super.c
    +++ b/fs/f2fs/super.c
    @@ -1172,7 +1172,7 @@ static void f2fs_put_super(struct super_block *sb)
    /* our cp_error case, we can wait for any writeback page */
    f2fs_flush_merged_writes(sbi);

    - f2fs_wait_on_all_pages_writeback(sbi);
    + f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);

    f2fs_bug_on(sbi, sbi->fsync_node_num);

    --
    2.20.1
    \
     
     \ /
      Last update: 2020-04-15 13:39    [W:4.075 / U:0.136 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site