Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [PATCH 5/5] x86,mm: make pagefault killable | Date | Wed, 23 Mar 2011 17:09:59 +0900 (JST) |
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> On Tue, 22 Mar 2011 20:09:29 +0900 (JST) > KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: > > > When oom killer occured, almost processes are getting stuck following > > two points. > > > > 1) __alloc_pages_nodemask > > 2) __lock_page_or_retry > > > > 1) is not much problematic because TIF_MEMDIE lead to make allocation > > failure and get out from page allocator. 2) is more problematic. When > > OOM situation, Zones typically don't have page cache at all and Memory > > starvation might lead to reduce IO performance largely. When fork bomb > > occur, TIF_MEMDIE task don't die quickly mean fork bomb may create > > new process quickly rather than oom-killer kill it. Then, the system > > may become livelock. > > > > This patch makes pagefault interruptible by SIGKILL. > > > > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > > --- > > arch/x86/mm/fault.c | 9 +++++++++ > > include/linux/mm.h | 1 + > > mm/filemap.c | 22 +++++++++++++++++----- > > 3 files changed, 27 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > > index 20e3f87..797c7d0 100644 > > --- 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; > > } else { > > if (regs->flags & X86_EFLAGS_IF) > > local_irq_enable(); > > @@ -1138,6 +1139,14 @@ good_area: > > } > > > > /* > > + * Pagefault was interrupted by SIGKILL. We have no reason to > > + * continue pagefault. > > + */ > > + if ((flags & FAULT_FLAG_KILLABLE) && (fault & VM_FAULT_RETRY) && > > + fatal_signal_pending(current)) > > + return; > > + > > Hmm? up_read(&mm->mmap_sem) ?
When __lock_page_or_retry() return 0, It call up_read(mmap_sem) in this function.
I agree this is strange (or ugly). but I don't want change this spec in this time.
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