From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 8B5106B0092 for ; Wed, 19 Jan 2011 17:19:20 -0500 (EST) Date: Wed, 19 Jan 2011 23:19:09 +0100 From: Andrea Arcangeli Subject: Re: [BUG] BUG: unable to handle kernel paging request at fffba000 Message-ID: <20110119221909.GO9506@random.random> References: <20110119124047.GA30274@kwango.lan.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110119124047.GA30274@kwango.lan.net> Sender: owner-linux-mm@kvack.org To: Ilya Dryomov Cc: linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org List-ID: Hello Ilya, thanks for sending me the gdb info too. can you test this fix? Thanks a lot! (it only affected x86 32bit builds with highpte enabled) ==== Subject: fix pte_unmap in khugepaged for highpte x86_32 From: Andrea Arcangeli __collapse_huge_page_copy is still dereferencing the pte passed as parameter so we must pte_unmap after __collapse_huge_page_copy returns, not before. Signed-off-by: Andrea Arcangeli --- diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 004c9c2..c4f634b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1837,9 +1837,9 @@ static void collapse_huge_page(struct mm_struct *mm, spin_lock(ptl); isolated = __collapse_huge_page_isolate(vma, address, pte); spin_unlock(ptl); - pte_unmap(pte); if (unlikely(!isolated)) { + pte_unmap(pte); spin_lock(&mm->page_table_lock); BUG_ON(!pmd_none(*pmd)); set_pmd_at(mm, address, pmd, _pmd); @@ -1856,6 +1856,7 @@ static void collapse_huge_page(struct mm_struct *mm, anon_vma_unlock(vma->anon_vma); __collapse_huge_page_copy(pte, new_page, vma, address, ptl); + pte_unmap(pte); __SetPageUptodate(new_page); pgtable = pmd_pgtable(_pmd); VM_BUG_ON(page_count(pgtable) != 1); -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org