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| author | Andrey Vagin <avagin@openvz.org> | 2011-03-09 15:22:23 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-03-23 13:16:39 -0700 |
| commit | d2ab16a60fa7873dffbb7c92eca6fc347f3ea80a (patch) | |
| tree | 61399c257bf56d5a98d00c7e139f786ff542d5b5 | |
| parent | ec3eb823853639a674a4fdea11b0a8f47437df0d (diff) | |
| download | lwn-d2ab16a60fa7873dffbb7c92eca6fc347f3ea80a.tar.gz lwn-d2ab16a60fa7873dffbb7c92eca6fc347f3ea80a.zip | |
x86/mm: Handle mm_fault_error() in kernel space
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 <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>
LKML-Reference: <201103092322.p29NMNPH001682@imap1.linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | 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 1739358b444d..8ac0d763fe2a 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -830,6 +830,13 @@ 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)) |