On Sat, Feb 25, 2017 at 09:50:32AM +0200, Andriy Gapon wrote: > On 24/02/2017 20:56, Jonathan T. Looney wrote: > > Author: jtl > > Date: Fri Feb 24 18:56:00 2017 > > New Revision: 314216 > > URL: https://svnweb.freebsd.org/changeset/base/314216 > > > > Log: > > We have seen several cases recently where we appear to get a double-fault: > > We have an original panic. Then, instead of writing the core to the dump > > device, the kernel has a second panic: "smp_targeted_tlb_shootdown: > > interrupts disabled". This change is an attempt to fix that second panic. > > Just curious if you were able to find out what code caused those shootdowns to > be sent. > It's pretty unusual for the after-panic code to do things like that. Memory allocations for busdma in coredumping path do that.
I know this from spending a lot of time making core dumps working with DMAR busdma. > > > > When the other CPUs are stopped, we can't notify them of the TLB > > shootdown, > > so we skip that operation. However, when the CPUs come back up, we > > invalidate the TLB to ensure they correctly observe any changes to the > > page mappings. > > > > Reviewed by: kib > > Sponsored by: Netflix > > Differential Revision: https://reviews.freebsd.org/D9786 > > > > Modified: > > head/sys/x86/x86/mp_x86.c > > > > Modified: head/sys/x86/x86/mp_x86.c > > ============================================================================== > > --- head/sys/x86/x86/mp_x86.c Fri Feb 24 17:36:55 2017 > > (r314215) > > +++ head/sys/x86/x86/mp_x86.c Fri Feb 24 18:56:00 2017 > > (r314216) > > @@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$"); > > #ifdef GPROF > > #include <sys/gmon.h> > > #endif > > +#include <sys/kdb.h> > > #include <sys/kernel.h> > > #include <sys/ktr.h> > > #include <sys/lock.h> > > @@ -1269,6 +1270,12 @@ cpustop_handler_post(u_int cpu) > > CPU_CLR_ATOMIC(cpu, &started_cpus); > > CPU_CLR_ATOMIC(cpu, &stopped_cpus); > > > > + /* > > + * We don't broadcast TLB invalidations to other CPUs when they are > > + * stopped. Hence, we clear the TLB before resuming. > > + */ > > + invltlb_glob(); > > + > > #if defined(__amd64__) && defined(DDB) > > amd64_db_resume_dbreg(); > > #endif > > @@ -1427,6 +1434,10 @@ smp_targeted_tlb_shootdown(cpuset_t mask > > uint32_t generation; > > int cpu; > > > > + /* It is not necessary to signal other CPUs while in the debugger. */ > > + if (kdb_active || panicstr != NULL) > > + return; > > + > > /* > > * Check for other cpus. Return if none. > > */ > > > > > -- > Andriy Gapon _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
