linux-kernel - [PATCH] mm: fix page_mkclean_one (was: 2.6.19 file content corruption on ext3)

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Date:	Wed, 20 Dec 2006 12:26:41 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Linus Torvalds <torvalds@...l.org>,
	Andrei Popa <andrei.popa@...eo.ro>,
	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hugh@...itas.com>,
	Florian Weimer <fw@...eb.enyo.de>,
	Marc Haber <mh+linux-kernel@...schlus.de>,
	Martin Michlmayr <tbm@...ius.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Arnd Bergmann <arnd.bergmann@...ibm.com>
Subject: [PATCH] mm: fix page_mkclean_one (was: 2.6.19 file content
	corruption on ext3)


fix page_mkclean_one()

it had several issues:
 - it failed to flush the cache
 - it failed to flush the tlb
 - it failed to do s390 (s390 guys, please verify this is now correct)

Also, clear in a loop to ensure SMP safeness as suggested by Arjan.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
 mm/rmap.c |   29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -432,7 +432,7 @@ static int page_mkclean_one(struct page 
 {
 	struct mm_struct *mm = vma->vm_mm;
 	unsigned long address;
-	pte_t *pte, entry;
+	pte_t *ptep;
 	spinlock_t *ptl;
 	int ret = 0;
 
@@ -440,22 +440,23 @@ static int page_mkclean_one(struct page 
 	if (address == -EFAULT)
 		goto out;
 
-	pte = page_check_address(page, mm, address, &ptl);
-	if (!pte)
+	ptep = page_check_address(page, mm, address, &ptl);
+	if (!ptep)
 		goto out;
 
-	if (!pte_dirty(*pte) && !pte_write(*pte))
-		goto unlock;
-
-	entry = ptep_get_and_clear(mm, address, pte);
-	entry = pte_mkclean(entry);
-	entry = pte_wrprotect(entry);
-	ptep_establish(vma, address, pte, entry);
-	lazy_mmu_prot_update(entry);
-	ret = 1;
+	while (pte_dirty(*ptep) || pte_write(*ptep)) {
+		pte_t entry = ptep_get_and_clear(mm, address, ptep);
+		flush_cache_page(vma, address, pte_pfn(entry));
+		flush_tlb_page(vma, address);
+		(void)page_test_and_clear_dirty(page); /* do the s390 thing */
+		entry = pte_wrprotect(entry);
+		entry = pte_mkclean(entry);
+		set_pte_at(vma, address, ptep, entry);
+		lazy_mmu_prot_update(entry);
+		ret = 1;
+	}
 
-unlock:
-	pte_unmap_unlock(pte, ptl);
+	pte_unmap_unlock(ptep, ptl);
 out:
 	return ret;
 }


-
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