Re: [PATCH 5/5] x86,mm: make pagefault killable
From: Oleg Nesterov <oleg@redhat.com>
Date: 2011-03-24 17:22:24
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On 03/22, KOSAKI Motohiro wrote:
This patch makes pagefault interruptible by SIGKILL.
Not a comment, but the question...
quoted hunk ↗ jump to hunk
--- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c@@ -1035,6 +1035,7 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code) if (user_mode_vm(regs)) { local_irq_enable(); error_code |= PF_USER; + flags |= FAULT_FLAG_KILLABLE;
OK, this is clear.
I am wondering, can't we set FAULT_FLAG_KILLABLE unconditionally
but check PF_USER when we get VM_FAULT_RETRY? I mean,
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
if (!(error_code & PF_USER))
no_context(...);
return;
}
Probably not... but I can't find any example of in-kernel fault which
can be broken by -EFAULT if current was killed.
mm_release()->put_user(clear_child_tid) should be fine...
Just curious, I feel I missed something obvious.
Oleg.
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