2013/5/17 Robert Love <rlove@xxxxxxxxxx>: > On Thu, May 16, 2013 at 1:19 PM, Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: >> On Thu, 16 May 2013 13:08:17 -0400 Robert Love <rlove@xxxxxxxxxx> wrote: >>> This problem seems a rare proper use of mutex_trylock. >> >> Not really. The need for a trylock is often an indication that a >> subsystem has a locking misdesign. That is indeed the case here. > > It is exactly the same as PF_MEMALLOC. We've got an effectively > asynchronous event (shrinking) that can occur while you are holding > locks requisite to that shrinking. Given that the shrinkage is best > effort, a trylock actually communicates the intent pretty well: "If > possible, grab this lock and shrink." > > I think the idiomatic fix is to introduce a GFP_SHMEM but that seems > overkill. Lots of the GFP flags are really just preventing recursing > into the shrinkage code and it seems ill-designed that we require > developers to know where they might end up. But we can disagree. :) > >> Well, it's not exactly a ton of work, but adding a per-ashmem_area lock >> to protect ->file would rather be putting lipstick on a pig. I suppose >> we can put the trylock in there and run away, but it wouldn't hurt to >> drop in a big fat comment somewhere explaining that the driver should be >> migrated to a per-object locking scheme. > > Unfortunately I think ashmem_shrink would need to grab the per-object > lock too; it needs to update the ranges. I'm sure we could re-design > this but I don't think it is as easy as simply pushing the locking > into the objects. > > Robert Hi all, I am wondering if this is fixed in latest kernel? We are continuously seeing this deadlock issue. Best Regards, Raul -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
