x86/mm: Handle mm_fault_error() in kernel space
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@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: <stable@kernel.org> LKML-Reference: <201103092322.p29NMNPH001682@imap1.linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -828,6 +828,13 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, unsigned int fault)
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{
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if (fault & VM_FAULT_OOM) {
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/* Kernel mode? Handle exceptions or die: */
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if (!(error_code & PF_USER)) {
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up_read(¤t->mm->mmap_sem);
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no_context(regs, error_code, address);
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return;
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}
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out_of_memory(regs, error_code, address);
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} else {
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if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
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