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Date:   Fri, 4 Dec 2020 09:54:01 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     Pavel Tatashin <pasha.tatashin@soleen.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        David Hildenbrand <david@redhat.com>,
        Oscar Salvador <osalvador@suse.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Sasha Levin <sashal@kernel.org>,
        Tyler Hicks <tyhicks@linux.microsoft.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, mike.kravetz@oracle.com,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, Jason Gunthorpe <jgg@ziepe.ca>,
        Peter Zijlstra <peterz@infradead.org>,
        Mel Gorman <mgorman@suse.de>,
        Matthew Wilcox <willy@infradead.org>,
        David Rientjes <rientjes@google.com>,
        John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH 5/6] mm: honor PF_MEMALLOC_NOMOVABLE for all allocations
Message-ID: <20201204085401.GB25569@dhcp22.suse.cz>
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On Fri 04-12-20 09:43:13, Michal Hocko wrote:
> On Thu 03-12-20 10:15:41, Pavel Tatashin wrote:
[...]
> > Also, current_gfp_context() is used elsewhere, and in some
> > places removing __GFP_MOVABLE from gfp_mask means that we will need to
> > also change other things. For example [1], in try_to_free_pages() we
> > call current_gfp_context(gfp_mask) which can reduce the maximum zone
> > idx, yet we simply set it to: reclaim_idx = gfp_zone(gfp_mask), not to
> > the newly determined gfp_mask.
> 
> Yes and the direct reclaim should honor the movable zone restriction.
> Why should we reclaim ZONE_MOVABLE when the allocation cannot really
> allocate from it? Or have I misunderstood your concern?

Btw. if we have gfp mask properly filtered for the fast path then we can
remove the additional call to current_gfp_context from the direct
reclaim path. Something for a separate patch.
-- 
Michal Hocko
SUSE Labs