From: Andrey Vagin <[email protected]> ------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
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: Paul Gortmaker <[email protected]> --- arch/x86/mm/fault.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 4c4508e..544ed25 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -831,6 +831,13 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code, 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)) -- 1.7.4.4 _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
