Commit 752dc185 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds

mm: fix warning in __set_page_dirty_nobuffers

New tmpfs use of !PageUptodate pages for fallocate() is triggering the
WARNING: at mm/page-writeback.c:1990 when __set_page_dirty_nobuffers()
is called from migrate_page_copy() for compaction.

It is anomalous that migration should use __set_page_dirty_nobuffers()
on an address_space that does not participate in dirty and writeback
accounting; and this has also been observed to insert surprising dirty
tags into a tmpfs radix_tree, despite tmpfs not using tags at all.

We should probably give migrate_page_copy() a better way to preserve the
tag and migrate accounting info, when mapping_cap_account_dirty().  But
that needs some more work: so in the interim, avoid the warning by using
a simple SetPageDirty on PageSwapBacked pages.
Reported-and-tested-by: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2f9d3df8
...@@ -436,7 +436,10 @@ void migrate_page_copy(struct page *newpage, struct page *page) ...@@ -436,7 +436,10 @@ void migrate_page_copy(struct page *newpage, struct page *page)
* is actually a signal that all of the page has become dirty. * is actually a signal that all of the page has become dirty.
* Whereas only part of our page may be dirty. * Whereas only part of our page may be dirty.
*/ */
__set_page_dirty_nobuffers(newpage); if (PageSwapBacked(page))
SetPageDirty(newpage);
else
__set_page_dirty_nobuffers(newpage);
} }
mlock_migrate_page(newpage, page); mlock_migrate_page(newpage, page);
......
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