On Fri, Nov 06, 2020 at 06:32:16PM +0100, Martin Wilck wrote: > On Thu, 2020-11-05 at 18:41 -0600, Benjamin Marzinski wrote: > > > > I can't make this segfault. So that looks good, but it does need > > libmultipath.version updated to include checker_thread_entry() > > Great news, thanks. Well the library version stuff hasn't been > committed yet anyway, this was against Christophe's current base. Actually, I ran into a different segfault with this patch. While the tur checker's libcheck_check() function is run under locking, so the device cannot be removed, The thread it creates is not. This means that it is possible for the device to get removed after libcheck_check() runs, but before checker_thread_entry() runs. In this case, when checker_thread_entry() is finally run, the passed in checker structure would already have been freed, causing a segfault. I have been able to easily reproduce this in the case where multipath device creation failed in the kernel. I'm pretty sure that the checker class needs its ref count increased before the thread is created, and the thread inself must only access the context, which should include a pointer to the class. -Ben > > @Christophe, any chance to move forward with the merge? > (then we can go ahead with this patch later, too...) > > Martin > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
