This is a note to let you know that I've just added the patch titled
x86/mm: Handle mm_fault_error() in kernel space
to the 2.6.37-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-mm-handle-mm_fault_error-in-kernel-space.patch
and it can be found in the queue-2.6.37 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From f86268549f424f83b9eb0963989270e14fbfc3de Mon Sep 17 00:00:00 2001
From: Andrey Vagin <[email protected]>
Date: Wed, 9 Mar 2011 15:22:23 -0800
Subject: x86/mm: Handle mm_fault_error() in kernel space
From: Andrey Vagin <[email protected]>
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 <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Linus Torvalds <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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|
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.37/x86-mm-handle-mm_fault_error-in-kernel-space.patch
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