[PATCH 04/48] mm/writeback: Improve __folio_mark_dirty() comment
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: 2021-12-08 04:23:13
Also in:
linux-mm
Subsystem:
memory management, page cache, the rest · Maintainers:
Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
Add some notes about how this function needs to be called. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- mm/page-writeback.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index a613f8ef6a02..91d163f8d36b 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c@@ -2496,7 +2496,11 @@ void folio_account_cleaned(struct folio *folio, struct address_space *mapping, * If warn is true, then emit a warning if the folio is not uptodate and has * not been truncated. * - * The caller must hold lock_page_memcg(). + * The caller must hold lock_page_memcg(). Most callers have the folio + * locked. A few have the folio blocked from truncation through other + * means (eg zap_page_range() has it mapped and is holding the page table + * lock). This can also be called from mark_buffer_dirty(), which I + * cannot prove is always protected against truncate. */ void __folio_mark_dirty(struct folio *folio, struct address_space *mapping, int warn)
--
2.33.0