> > On Thu, 19 Aug 2010, KOSAKI Motohiro wrote: > > > > > > This is especially necessary to solve an mm->mmap_sem livelock issue > > > > whereas an oom killed thread must acquire the lock in the exit path while > > > > another thread is holding it in the page allocator while trying to > > > > allocate memory itself (and will preempt the oom killer since a task was > > > > already killed). Since tasks with pending fatal signals are now granted > > > > access to memory reserves, the thread holding the lock may quickly > > > > allocate and release the lock so that the oom killed task may exit. > > > > > > I can't understand this sentence. mm sharing is happen when vfork, That > > > said, parent process is always sleeping. why do we need to worry that parent > > > process is holding mmap_sem? > > > > > > > No, I'm talking about threads with CLONE_VM and not CLONE_THREAD (or > > CLONE_VFORK, in your example). They share the same address space but are > > in different tgid's and may sit holding mm->mmap_sem looping in the page > > allocator while we know we're oom and there's no chance of freeing any > > more memory since the oom killer doesn't kill will other tasks have yet to > > exit. > > Why don't you use pthread library? Is there any good reason? That said, > If you are trying to optimize neither thread nor vfork case, I'm not charmed > this because 99.99% user don't use it. but even though every user will get > performance degression. Can you please consider typical use case optimization? That said, This was NAKed while this patch makes end user unhappy. please fix it. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>