On Mon 03-04-17 14:57:11, Andrey Ryabinin wrote: > On 04/03/2017 11:47 AM, Michal Hocko wrote: > > On Fri 31-03-17 10:00:30, Shakeel Butt wrote: [...] > >>> @@ -1017,9 +1018,7 @@ static int zswap_frontswap_store(unsigned type, > >>> pgoff_t offset, > >>> > >>> /* store */ > >>> len = dlen + sizeof(struct zswap_header); > >>> - ret = zpool_malloc(entry->pool->zpool, len, > >>> - __GFP_NORETRY | __GFP_NOWARN | > >>> __GFP_KSWAPD_RECLAIM, > >>> - &handle); > >>> + ret = zpool_malloc(entry->pool->zpool, len, gfp, &handle); > > > > and here we used to do GFP_NOWAIT alternative already. What is going on > > here? > > > I suspect that there was no particular reason to assemble this > custom set of gfp flags. This code probably should have been using > GFP_NOWAIT|__GFP_NOWARN from the very beginning.
Or just use GFP_KERNEL with a comment that this is called from the reclaim context and as such is properly addressed at the page allocator layer. One reason why this makes more sense than GFP_NOWAIT is that this is easier to follow. When you see GFP_NOWAIT then you usually expect a best efford opportunistic allocation attempt (especially with __GFP_NOWARN) which is not the case here because this paths gets a full memory reserves access. If this is not intentional then use GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN. -- Michal Hocko SUSE Labs
