• Andrey Vagin's avatar
    x86/mm: Handle mm_fault_error() in kernel space · f8626854
    Andrey Vagin authored
    
    
    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: default avatarAndrey Vagin <avagin@openvz.org>
    Signed-off-by: default avatarAndrew 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: default avatarIngo Molnar <mingo@elte.hu>
    f8626854
fault.c 27.5 KB