On Tue, May 10, 2016 at 02:30:11PM +0200, Vlastimil Babka wrote: > On 05/10/2016 01:28 PM, Tetsuo Handa wrote: > > Vlastimil Babka wrote: > >> In __alloc_pages_slowpath(), alloc_flags doesn't change after it's initialized, > >> so move the initialization above the retry: label. Also make the comment above > >> the initialization more descriptive. > > > > Not true. gfp_to_alloc_flags() will include ALLOC_NO_WATERMARKS if current > > thread got TIF_MEMDIE after gfp_to_alloc_flags() was called for the first > > Oh, right. Stupid global state. > > > time. Do you want to make TIF_MEMDIE threads fail their allocations without > > using memory reserves? > > No, thanks for catching this. How about the following version? I think > that's even nicer cleanup, if correct. Note it causes a conflict in > patch 03/13 but it's simple to resolve. > > Thanks > > ----8<---- > >From 68f09f1d4381c7451238b4575557580380d8bf30 Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka <vbabka@xxxxxxx> > Date: Fri, 29 Apr 2016 11:51:17 +0200 > Subject: [RFC 02/13] mm, page_alloc: set alloc_flags only once in slowpath > > In __alloc_pages_slowpath(), alloc_flags doesn't change after it's initialized, > so move the initialization above the retry: label. Also make the comment above > the initialization more descriptive. > > The only exception in the alloc_flags being constant is ALLOC_NO_WATERMARKS, > which may change due to TIF_MEMDIE being set on the allocating thread. We can > fix this, and make the code simpler and a bit more effective at the same time, > by moving the part that determines ALLOC_NO_WATERMARKS from > gfp_to_alloc_flags() to gfp_pfmemalloc_allowed(). This means we don't have to > mask out ALLOC_NO_WATERMARKS in several places in __alloc_pages_slowpath() > anymore. The only test for the flag can instead call gfp_pfmemalloc_allowed(). Your patch looks correct to me but it makes me wonder something. Why do we need to mask out ALLOC_NO_WATERMARKS in several places? If some requestors have ALLOC_NO_WATERMARKS flag, he will eventually do ALLOC_NO_WATERMARKS allocation in retry loop. I don't understand what's the merit of masking out it. Thanks. -- 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>