Messages in this thread | | | Subject | Re: [PATCH v12 22/22] selftests/vm: Fix deadlock in protection_keys.c | From | Dave Hansen <> | Date | Fri, 16 Mar 2018 15:34:52 -0700 |
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On 02/21/2018 05:55 PM, Ram Pai wrote: > From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> > > The sig_chld() handler calls dprintf2() taking care of setting > dprint_in_signal so that sigsafe_printf() won't call printf(). > Unfortunately, this precaution is is negated by dprintf_level(), which > has a call to fflush(). > > This function acquires a lock, which means that if the signal interrupts an > ongoing fflush() the process will deadlock. At least on powerpc this is > easy to trigger, resulting in the following backtrace when attaching to the > frozen process:
Ugh, yeah, I've run into this too.
Acked-by: Dave Hansen <dave.hansen@intel.com>
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