lkml.org 
[lkml]   [2019]   [Oct]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mm/thp: fix deadlock in collapse_file()
Date
As syzbot reported, we cannot call filemap_flush() with the page locked.
Remove the filemap_flush() as it is not required. khugepaged would just
wait until the page is flushed naturally.

Reported-by: syzbot+efb9e48b9fbdc49bb34a@syzkaller.appspotmail.com
Fixes: 9d840e58caa0 ("mmthp-recheck-each-page-before-collapsing-file-thp-v4")
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
mm/khugepaged.c | 10 +---------
1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index cd480dce92c6..3ec5333ae94d 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1640,16 +1640,8 @@ static void collapse_file(struct mm_struct *mm,
/*
* khugepaged only works on read-only fd, so this
* page is dirty because it hasn't been flushed
- * since first write. There won't be new dirty
- * pages.
- *
- * Trigger async flush here and hope the writeback
- * is done when khugepaged revisits this page.
- *
- * This is a one-off situation. We are not forcing
- * writeback in loop.
+ * since first write.
*/
- filemap_flush(mapping);
result = SCAN_FAIL;
goto out_unlock;
}
--
2.17.1
\
 
 \ /
  Last update: 2019-10-28 23:15    [W:0.021 / U:0.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site