Messages in this thread | | | Date | Tue, 15 Feb 2011 20:26:51 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] fix pgd_lock deadlock |
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On Tue, 15 Feb 2011, Andrea Arcangeli wrote:
> Hello, > > Without this patch we can deadlock in the page_table_lock with NR_CPUS > < 4 or THP on, with this patch we hopefully won't deadlock in the > pgd_lock (if taken from irq). I can't see anything taking it from irq > (maybe aio? to check I also tried the libaio testuite with no apparent > VM_BUG_ON triggering), so unless somebody sees it, I think we should > apply it. I've been running for a while with this patch applied > without apparent problems. Other archs may follow suit if it's proven > that there's nothing taking the pgd_lock from irq. > > === > Subject: fix pgd_lock deadlock > > From: Andrea Arcangeli <aarcange@redhat.com> > > It's forbidden to take the page_table_lock with the irq disabled or if there's > contention the IPIs (for tlb flushes) sent with the page_table_lock held will > never run leading to a deadlock.
I really read this thing 5 times and still cannot make any sense of it.
You talk about page_table_lock and then fiddle with pgd_lock.
-ENOSENSE
tglx
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