From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shakeel Butt Subject: [PATCH 2/4] memcg: unify force charging conditions Date: Thu, 10 Feb 2022 00:14:35 -0800 Message-ID: <20220210081437.1884008-3-shakeelb@google.com> References: <20220210081437.1884008-1-shakeelb@google.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=fMIRROeDCCygpucOKIXnuDRE53blx2Fd4oRcgvywHRM=; b=FRPbX4D29kIW+qlbRohcly9kDDAZugoZr12c4pn83sXCQupHVz5i02c232pWifGcJX f2VKxeODp/d70mILcDiRehpZ84CcGH2l4Jn8IWMs4foCylEa2D1UArVeTuzjixJC4rGk b0lpopdNyBq7R31A1Xpm2gJf9dqmgq86WKoAW4JWyZkT0TVi9iUwsw/k72UOWMw0GRU/ QwbJNQCB1nO+jRIaSvwfKU42p7UXYBKyV9mgSFEGC+oPAVPT/hlWXU2lWmHOp6OqocJT xCfPQ42G1pJE/BGDOmZi69jA2Ce89s0XXfjxxywhmito7sKfPstoFHyxIl1vspcP3YBe 8Ucw== In-Reply-To: <20220210081437.1884008-1-shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Johannes Weiner , Michal Hocko , Roman Gushchin Cc: Chris Down , Andrew Morton , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shakeel Butt Currently the kernel force charges the allocations which have __GFP_HIGH flag without triggering the memory reclaim. __GFP_HIGH indicates that the caller is high priority and since commit 869712fd3de5 ("mm: memcontrol: fix network errors from failing __GFP_ATOMIC charges") the kernel let such allocations do force charging. Please note that __GFP_ATOMIC has been replaced by __GFP_HIGH. __GFP_HIGH does not tell if the caller can block or can trigger reclaim. There are separate checks to determine that. So, there is no need to skip reclaim for __GFP_HIGH allocations. So, handle __GFP_HIGH together with __GFP_NOFAIL which also does force charging. Please note that this is a noop change as there are no __GFP_HIGH allocators in kernel which also have __GFP_ACCOUNT (or SLAB_ACCOUNT) and does not allow reclaim for now. The reason for this patch is to simplify the reasoning of the following patches. Signed-off-by: Shakeel Butt --- mm/memcontrol.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c40c27822802..ae73a40818b0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2560,15 +2560,6 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, goto retry; } - /* - * Memcg doesn't have a dedicated reserve for atomic - * allocations. But like the global atomic pool, we need to - * put the burden of reclaim on regular allocation requests - * and let these go through as privileged allocations. - */ - if (gfp_mask & __GFP_HIGH) - goto force; - /* * Prevent unbounded recursion when reclaim operations need to * allocate memory. This might exceed the limits temporarily, @@ -2642,7 +2633,13 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, goto retry; } nomem: - if (!(gfp_mask & __GFP_NOFAIL)) + /* + * Memcg doesn't have a dedicated reserve for atomic + * allocations. But like the global atomic pool, we need to + * put the burden of reclaim on regular allocation requests + * and let these go through as privileged allocations. + */ + if (!(gfp_mask & (__GFP_NOFAIL | __GFP_HIGH))) return -ENOMEM; force: /* -- 2.35.1.265.g69c8d7142f-goog