> On Tue, Nov 17, 2009 at 04:23:43PM +0900, KOSAKI Motohiro wrote: > > > > Non MM subsystem must not use PF_MEMALLOC. Memory reclaim need few > > memory, anyone must not prevent it. Otherwise the system cause > > mysterious hang-up and/or OOM Killer invokation. > > The xfsbufd is a woken run by a registered memory shaker. i.e. it > runs when the system needs to reclaim memory. It forceѕ the > delayed write metadata buffers (of which there can be a lot) to disk > so that they can be reclaimed on IO completion. This IO submission > may require ѕome memory to be allocated to be able to free that > memory. > > Hence, AFAICT the use of PF_MEMALLOC is valid here. Thanks a lot. I have one additional question, may I ask you? How can we calculate maximum memory usage in xfsbufd? I'm afraid that VM and XFS works properly but adding two makes memory exhaust. And, I conclude XFS doesn't need sharing reservation memory with VM, it only need non failed allocation. right? IOW I'm prefer perter's suggestion. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
