2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ 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]> Signed-off-by: Andi Kleen <[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(+) Index: linux-2.6.35.y/arch/x86/mm/fault.c =================================================================== --- linux-2.6.35.y.orig/arch/x86/mm/fault.c 2011-03-29 22:50:46.520068086 -0700 +++ linux-2.6.35.y/arch/x86/mm/fault.c 2011-03-29 23:03:02.185244254 -0700 @@ -831,6 +831,13 @@ 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)) _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
