On Wed, 6 May 2015 19:50:24 +0200 David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx> wrote: > As Peter asked me to also do the decoupling in one shot, this is > the new series. > > I recently discovered that might_fault() doesn't call might_sleep() > anymore. Therefore bugs like: > > spin_lock(&lock); > rc = copy_to_user(...); > spin_unlock(&lock); > > would not be detected with CONFIG_DEBUG_ATOMIC_SLEEP. The code was > changed to disable false positives for code like: > > pagefault_disable(); > rc = copy_to_user(...); > pagefault_enable(); > > Whereby the caller wants do deal with failures. hm, that was a significant screwup. I wonder how many bugs we subsequently added. > > .. > > This series therefore does 2 things: > > > 1. Decouple pagefault_disable() from preempt_enable() > > ... > > 2. Reenable might_sleep() checks for might_fault() All seems sensible to me. pagefault_disabled has to go into the task_struct (rather than being per-cpu) because pagefault_disabled_inc() doesn't disable preemption, yes? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>