From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936207Ab1KJD6A (ORCPT ); Wed, 9 Nov 2011 22:58:00 -0500 Received: from cantor2.suse.de ([195.135.220.15]:45079 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965965Ab1KJDrw (ORCPT ); Wed, 9 Nov 2011 22:47:52 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Nov 9 13:32:06 2011 Message-Id: <20111109213206.449167598@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 09 Nov 2011 13:34:45 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Anton Blanchard , Benjamin Herrenschmidt Subject: [238/264] powerpc: Fix deadlock in icswx code In-Reply-To: <20111109213508.GA3476@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Anton Blanchard commit 8bdafa39a47265bc029838b35cc6585f69224afa upstream. The icswx code introduced an A-B B-A deadlock: CPU0 CPU1 ---- ---- lock(&anon_vma->mutex); lock(&mm->mmap_sem); lock(&anon_vma->mutex); lock(&mm->mmap_sem); Instead of using the mmap_sem to keep mm_users constant, take the page table spinlock. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/mm/mmu_context_hash64.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/arch/powerpc/mm/mmu_context_hash64.c +++ b/arch/powerpc/mm/mmu_context_hash64.c @@ -136,8 +136,8 @@ int use_cop(unsigned long acop, struct m if (!mm || !acop) return -EINVAL; - /* We need to make sure mm_users doesn't change */ - down_read(&mm->mmap_sem); + /* The page_table_lock ensures mm_users won't change under us */ + spin_lock(&mm->page_table_lock); spin_lock(mm->context.cop_lockp); if (mm->context.cop_pid == COP_PID_NONE) { @@ -164,7 +164,7 @@ int use_cop(unsigned long acop, struct m out: spin_unlock(mm->context.cop_lockp); - up_read(&mm->mmap_sem); + spin_unlock(&mm->page_table_lock); return ret; } @@ -185,8 +185,8 @@ void drop_cop(unsigned long acop, struct if (WARN_ON_ONCE(!mm)) return; - /* We need to make sure mm_users doesn't change */ - down_read(&mm->mmap_sem); + /* The page_table_lock ensures mm_users won't change under us */ + spin_lock(&mm->page_table_lock); spin_lock(mm->context.cop_lockp); mm->context.acop &= ~acop; @@ -213,7 +213,7 @@ void drop_cop(unsigned long acop, struct } spin_unlock(mm->context.cop_lockp); - up_read(&mm->mmap_sem); + spin_unlock(&mm->page_table_lock); } EXPORT_SYMBOL_GPL(drop_cop);