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Message-Id: <20110321230711.337361825@clark.kroah.org>
Date: Mon, 21 Mar 2011 16:06:20 -0700
From: Greg KH <gregkh@...e.de>
To: linux-kernel@...r.kernel.org, stable@...nel.org
Cc: stable-review@...nel.org, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
Andrey Vagin <avagin@...nvz.org>,
"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>
Subject: [21/87] x86/mm: Handle mm_fault_error() in kernel space
2.6.37-stable review patch. If anyone has any objections, please let us know.
------------------
From: Andrey Vagin <avagin@...nvz.org>
commit f86268549f424f83b9eb0963989270e14fbfc3de upstream.
mm_fault_error() should not execute oom-killer, if page fault
occurs in kernel space. E.g. in copy_from_user()/copy_to_user().
This would happen if we find ourselves in OOM on a
copy_to_user(), or a copy_from_user() which faults.
Without this patch, the kernels hangs up in copy_from_user(),
because OOM killer sends SIG_KILL to current process, but it
can't handle a signal while in syscall, then the kernel returns
to copy_from_user(), reexcute current command and provokes
page_fault again.
With this patch the kernel return -EFAULT from copy_from_user().
The code, which checks that page fault occurred in kernel space,
has been copied from do_sigbus().
This situation is handled by the same way on powerpc, xtensa,
tile, ...
Signed-off-by: Andrey Vagin <avagin@...nvz.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
LKML-Reference: <201103092322.p29NMNPH001682@...p1.linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
arch/x86/mm/fault.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -827,6 +827,13 @@ mm_fault_error(struct pt_regs *regs, uns
unsigned long address, unsigned int fault)
{
if (fault & VM_FAULT_OOM) {
+ /* Kernel mode? Handle exceptions or die: */
+ if (!(error_code & PF_USER)) {
+ up_read(¤t->mm->mmap_sem);
+ no_context(regs, error_code, address);
+ return;
+ }
+
out_of_memory(regs, error_code, address);
} else {
if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
--
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