The patch titled
x86/mm: handle mm_fault_error() in kernel space
has been removed from the -mm tree. Its filename was
x86-mm-handle-mm_fault_error-in-kernel-space.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: x86/mm: handle mm_fault_error() in kernel space
From: Andrey Vagin <avagin@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/fault.c | 7 +++++++
1 file changed, 7 insertions(+)
diff -puN arch/x86/mm/fault.c~x86-mm-handle-mm_fault_error-in-kernel-space arch/x86/mm/fault.c
--- a/arch/x86/mm/fault.c~x86-mm-handle-mm_fault_error-in-kernel-space
+++ a/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 -mm which might be from avagin@xxxxxxxxxx are
linux-next.patch
oom-prevent-unnecessary-oom-kills-or-kernel-panics.patch
oom-skip-zombies-when-iterating-tasklist.patch
fs-devpts-inodec-correctly-check-d_alloc_name-return-code-in-devpts_pty_new.patch
fs-devpts_pty_new-return-enomem-if-dentry-allocation-failed.patch
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