From: Andrew Morton <akpm@osdl.org>
To: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] s390: lost dirty bits.
Date: Tue, 15 Jun 2004 21:09:19 -0700 [thread overview]
Message-ID: <20040615210919.1c82a5c8.akpm@osdl.org> (raw)
In-Reply-To: <20040615174436.GA10098@mschwid3.boeblingen.de.ibm.com>
Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:
>
> The SetPageUptodate function is called for pages that are already
> up to date. The arch_set_page_uptodate function of s390 may not
> clear the dirty bit in that case otherwise a dirty bit which is set
> between the start of an i/o for a writeback and a following call
> to SetPageUptodate is lost.
>
> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
>
> diffstat:
>
> --- linux-2.5/include/asm-s390/pgtable.h 24 Mar 2004 18:18:22 -0000 1.23
> +++ linux-2.5/include/asm-s390/pgtable.h 15 Jun 2004 16:43:35 -0000 1.23.2.1
> @@ -652,7 +652,8 @@
>
> #define arch_set_page_uptodate(__page) \
> do { \
> - asm volatile ("sske %0,%1" : : "d" (0), \
> + if (!PageUptodate(__page)) \
> + asm volatile ("sske %0,%1" : : "d" (0), \
> "a" (__pa((__page-mem_map) << PAGE_SHIFT)));\
> } while (0)
Do you know what the call path for the redundant SetpageUptodate() is?
This patch still has a little race - it'd be better to override _all_ of
SetPageUptodate() in page-flags.h and do:
if (!test_and_set_bit(PG_uptodate, &page->flags))
...
--- 25/include/asm-s390/pgtable.h~s390-lost-dirty-bits 2004-06-15 21:02:00.621441504 -0700
+++ 25-akpm/include/asm-s390/pgtable.h 2004-06-15 21:06:43.391453928 -0700
@@ -656,7 +656,8 @@ static inline pte_t mk_pte_phys(unsigned
#define arch_set_page_uptodate(__page) \
do { \
- asm volatile ("sske %0,%1" : : "d" (0), \
+ if (!test_and_set_bit(PG_uptodate, __page)) \
+ asm volatile ("sske %0,%1" : : "d" (0), \
"a" (__pa((__page-mem_map) << PAGE_SHIFT)));\
} while (0)
diff -puN include/linux/page-flags.h~s390-lost-dirty-bits include/linux/page-flags.h
--- 25/include/linux/page-flags.h~s390-lost-dirty-bits 2004-06-15 21:04:58.982326528 -0700
+++ 25-akpm/include/linux/page-flags.h 2004-06-15 21:08:30.493171992 -0700
@@ -194,16 +194,12 @@ extern unsigned long __read_page_state(u
#define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
-#ifndef arch_set_page_uptodate
-#define arch_set_page_uptodate(page) do { } while (0)
+#ifdef arch_set_page_uptodate
+#define SetPageUptodate(page) arch_set_page_uptodate(page)
+#else
+#define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags)
#endif
-
#define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags)
-#define SetPageUptodate(page) \
- do { \
- arch_set_page_uptodate(page); \
- set_bit(PG_uptodate, &(page)->flags); \
- } while (0)
#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
#define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
_
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next prev parent reply other threads:[~2004-06-16 4:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-15 17:44 Martin Schwidefsky
2004-06-16 4:09 ` Andrew Morton [this message]
2004-06-16 7:12 ` Christoph Hellwig
2004-06-16 8:42 Martin Schwidefsky
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