From: Nick Piggin <npiggin@suse.de>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: [patch] mm: fix assertion
Date: Wed, 14 Jan 2009 07:28:16 +0100 [thread overview]
Message-ID: <20090114062816.GA15671@wotan.suse.de> (raw)
(I ran into this when debugging the lockless pagecache barrier problem btw)
--
This assertion is incorrect for lockless pagecache. By definition if we have an
unpinned page that we are trying to take a speculative reference to, it may
become the tail of a compound page at any time (if it is freed, then reallocated
as a compound page).
It was still a valid assertion for the vmscan.c LRU isolation case, but it
doesn't seem incredibly helpful... if somebody wants it, they can put it back
directly where it applies in the vmscan code.
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h 2009-01-05 14:53:29.000000000 +1100
+++ linux-2.6/include/linux/mm.h 2009-01-05 14:53:54.000000000 +1100
@@ -270,7 +270,6 @@ static inline int put_page_testzero(stru
*/
static inline int get_page_unless_zero(struct page *page)
{
- VM_BUG_ON(PageTail(page));
return atomic_inc_not_zero(&page->_count);
}
--
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next reply other threads:[~2009-01-14 6:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-14 6:28 Nick Piggin [this message]
2009-01-15 17:35 ` [patch] mm: fix assertion Christoph Lameter
2009-01-16 2:57 ` Nick Piggin
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