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Message-Id: <1406067727-19683-59-git-send-email-kamal@canonical.com> Date: Tue, 22 Jul 2014 15:21:09 -0700 From: Kamal Mostafa <kamal@...onical.com> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org, kernel-team@...ts.ubuntu.com Cc: Tony Luck <tony.luck@...el.com>, Naoya Horiguchi <n-horiguchi@...jp.nec.com>, Andi Kleen <andi@...stfloor.org>, Borislav Petkov <bp@...e.de>, Chen Gong <gong.chen@...ux.jf.intel.com>, Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Kamal Mostafa <kamal@...onical.com> Subject: [PATCH 3.8 058/116] mm/memory-failure.c: don't let collect_procs() skip over processes for MF_ACTION_REQUIRED 3.8.13.27 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Tony Luck <tony.luck@...el.com> commit 74614de17db6fb472370c426d4f934d8d616edf2 upstream. 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 <tony.luck@...el.com> Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com> Cc: Andi Kleen <andi@...stfloor.org> Cc: Borislav Petkov <bp@...e.de> Cc: Chen Gong <gong.chen@...ux.jf.intel.com> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> Signed-off-by: Kamal Mostafa <kamal@...onical.com> --- 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 0af800c..7f3ceb1 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -382,10 +382,12 @@ 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; @@ -395,7 +397,7 @@ 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; @@ -411,7 +413,7 @@ 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) { @@ -430,7 +432,7 @@ 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; @@ -441,7 +443,7 @@ 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, @@ -467,7 +469,8 @@ 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; @@ -478,9 +481,9 @@ 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); } @@ -950,7 +953,7 @@ 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); if (hpage != ppage) lock_page(ppage); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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