From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 15 Jun 2004 21:09:19 -0700 From: Andrew Morton Subject: Re: [PATCH] s390: lost dirty bits. Message-Id: <20040615210919.1c82a5c8.akpm@osdl.org> In-Reply-To: <20040615174436.GA10098@mschwid3.boeblingen.de.ibm.com> References: <20040615174436.GA10098@mschwid3.boeblingen.de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Martin Schwidefsky Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: Martin Schwidefsky 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 > > 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) _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org