From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754582AbaETRm1 (ORCPT ); Tue, 20 May 2014 13:42:27 -0400 Received: from mga03.intel.com ([143.182.124.21]:12542 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754540AbaETRmF (ORCPT ); Tue, 20 May 2014 13:42:05 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,875,1392192000"; d="scan'208";a="434624263" Message-Id: In-Reply-To: References: From: Tony Luck Date: Tue, 20 May 2014 09:46:43 -0700 Subject: [PATCH 2/2] memory-failure: Don't let collect_procs() skip over processes for MF_ACTION_REQUIRED To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Andi Kleen , Borislav Petkov , Chen Gong Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When Linux sees an "action optional" machine check (where h/w has reported an error that is not in the current execution path) we generally do not want to signal a process, since most processes do not have a SIGBUS handler - we'd just prematurely terminate the process for a problem that they might never actually see. task_early_kill() decides whether to consider a process - and it checks whether this specific process has been marked for early signals with "prctl", or if the system administrator has requested early signals for all processes using /proc/sys/vm/memory_failure_early_kill. But for MF_ACTION_REQUIRED case we must not defer. The error is in the execution path of the current thread so we must send the SIGBUS immediatley. Fix by passing a flag argument through collect_procs*() to task_early_kill() so it knows whether we can defer or must take action. Signed-off-by: Tony Luck --- mm/memory-failure.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 642c8434b166..f0967f72991c 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -380,10 +380,12 @@ static void kill_procs(struct list_head *to_kill, int forcekill, int trapno, } } -static int task_early_kill(struct task_struct *tsk) +static int task_early_kill(struct task_struct *tsk, int force_early) { if (!tsk->mm) return 0; + if (force_early) + return 1; if (tsk->flags & PF_MCE_PROCESS) return !!(tsk->flags & PF_MCE_EARLY); return sysctl_memory_failure_early_kill; @@ -393,7 +395,7 @@ static int task_early_kill(struct task_struct *tsk) * Collect processes when the error hit an anonymous page. */ static void collect_procs_anon(struct page *page, struct list_head *to_kill, - struct to_kill **tkc) + struct to_kill **tkc, int force_early) { struct vm_area_struct *vma; struct task_struct *tsk; @@ -409,7 +411,7 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill, for_each_process (tsk) { struct anon_vma_chain *vmac; - if (!task_early_kill(tsk)) + if (!task_early_kill(tsk, force_early)) continue; anon_vma_interval_tree_foreach(vmac, &av->rb_root, pgoff, pgoff) { @@ -428,7 +430,7 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill, * Collect processes when the error hit a file mapped page. */ static void collect_procs_file(struct page *page, struct list_head *to_kill, - struct to_kill **tkc) + struct to_kill **tkc, int force_early) { struct vm_area_struct *vma; struct task_struct *tsk; @@ -439,7 +441,7 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill, for_each_process(tsk) { pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); - if (!task_early_kill(tsk)) + if (!task_early_kill(tsk, force_early)) continue; vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, @@ -465,7 +467,8 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill, * First preallocate one tokill structure outside the spin locks, * so that we can kill at least one process reasonably reliable. */ -static void collect_procs(struct page *page, struct list_head *tokill) +static void collect_procs(struct page *page, struct list_head *tokill, + int force_early) { struct to_kill *tk; @@ -476,9 +479,9 @@ static void collect_procs(struct page *page, struct list_head *tokill) if (!tk) return; if (PageAnon(page)) - collect_procs_anon(page, tokill, &tk); + collect_procs_anon(page, tokill, &tk, force_early); else - collect_procs_file(page, tokill, &tk); + collect_procs_file(page, tokill, &tk, force_early); kfree(tk); } @@ -963,7 +966,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn, * there's nothing that can be done. */ if (kill) - collect_procs(ppage, &tokill); + collect_procs(ppage, &tokill, flags & MF_ACTION_REQUIRED); ret = try_to_unmap(ppage, ttu); if (ret != SWAP_SUCCESS) -- 1.8.4.1