Fix zpool on zvol deadlock

[zfs.git] / module / zfs / zpl_file.c

diff --git a/module/zfs/zpl_file.c b/module/zfs/zpl_file.c
index 5ac41c9..9c27b7f 100644 (file)
--- a/module/zfs/zpl_file.c
+++ b/module/zfs/zpl_file.c
@@ -357,21 +357,16 @@ zpl_putpage(struct page *pp, struct writeback_control *wbc, void *data)
 
        ASSERT(PageLocked(pp));
        ASSERT(!PageWriteback(pp));
+       ASSERT(!(current->flags & PF_NOFS));
 
        /*
-        * Disable the normal reclaim path for zpl_putpage().  This
-        * ensures that all memory allocations under this call path
-        * will never enter direct reclaim.  If this were to happen
-        * the VM might try to write out additional pages by calling
-        * zpl_putpage() again resulting in a deadlock.
+        * Annotate this call path with a flag that indicates that it is
+        * unsafe to use KM_SLEEP during memory allocations due to the
+        * potential for a deadlock.  KM_PUSHPAGE should be used instead.
         */
-       if (current->flags & PF_MEMALLOC) {
-               (void) zfs_putpage(mapping->host, pp, wbc);
-       } else {
-               current->flags |= PF_MEMALLOC;
-               (void) zfs_putpage(mapping->host, pp, wbc);
-               current->flags &= ~PF_MEMALLOC;
-       }
+       current->flags |= PF_NOFS;
+       (void) zfs_putpage(mapping->host, pp, wbc);
+       current->flags &= ~PF_NOFS;
 
        return (0);
 }