On 12/01/2018 19:18, Matthew Wilcox wrote: > On Fri, Jan 12, 2018 at 06:26:02PM +0100, Laurent Dufour wrote: >> There is a deadlock when a CPU is doing a speculative page fault and >> another one is calling do_unmap(). >> >> The deadlock occurred because the speculative path try to spinlock the >> pte while the interrupt are disabled. When the other CPU in the >> unmap's path has locked the pte then is waiting for all the CPU to >> invalidate the TLB. As the CPU doing the speculative fault have the >> interrupt disable it can't invalidate the TLB, and can't get the lock. >> >> Since we are in a speculative path, we can race with other mm action. >> So let assume that the lock may not get acquired and fail the >> speculative page fault. > > It seems like you introduced this bug in the previous patch, and now > you're fixing it in this patch? Why not merge the two? You're right this is a fix from the previous patch. Initially my idea was to keep the original Peter's patch as is, but sounds that this is not a good idea. I'll merge it in the previous one. Thanks, Laurent. -- 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>
