From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DAAFC433E0 for ; Thu, 28 Jan 2021 23:48:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9D03664DFC for ; Thu, 28 Jan 2021 23:48:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D03664DFC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E762E6B0005; Thu, 28 Jan 2021 18:48:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E00456B0006; Thu, 28 Jan 2021 18:48:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C79F86B006C; Thu, 28 Jan 2021 18:48:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0050.hostedemail.com [216.40.44.50]) by kanga.kvack.org (Postfix) with ESMTP id AF3E76B0005 for ; Thu, 28 Jan 2021 18:48:10 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 7476C363E for ; Thu, 28 Jan 2021 23:48:10 +0000 (UTC) X-FDA: 77756824740.30.help48_060f7cd275a3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id 50080180B3C83 for ; Thu, 28 Jan 2021 23:48:10 +0000 (UTC) X-HE-Tag: help48_060f7cd275a3 X-Filterd-Recvd-Size: 8153 Received: from mail-ej1-f46.google.com (mail-ej1-f46.google.com [209.85.218.46]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Jan 2021 23:48:09 +0000 (UTC) Received: by mail-ej1-f46.google.com with SMTP id hs11so10392658ejc.1 for ; Thu, 28 Jan 2021 15:48:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=MDptI0q5U2/k2B8+Dz8XvhuiC5p5Hg1baqnbya2iA58=; b=KrMIGBIJjYTOYTJaUf/dWAxgCpZjVe7BL453jkSk8NzKOXuenPQHDs4bDK6hLyU9/c W69nCP88c/yFbqyJgqMxBWQSvGfUaHFICxVld+pQ5G9A6YznDKqsdGGY/6lWM12KY9Kx FXVtPOq1n7JQcZme766f5TXo3PDrylPiiu7USTDHW/0EPaAJjQPDXpU+oOOwcjo8G/jY lmCbB5b7bF9ZSXqlVFz3+n/G4iEnIfXzIZpQF1B5MRYyhFeZ5NzBP17ffDnPAN7YV9vd Vxjk/PGmJnwqhgnHBGBeVHcdGyJMyVkrQ8rJeQTKcrQepBsPLSugUN7BRnWvGgge+cPY mS+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MDptI0q5U2/k2B8+Dz8XvhuiC5p5Hg1baqnbya2iA58=; b=B7kA310c55omO7wkELCZ7IXcd14G77RmPWKt7qTJa1M0h0xkZWt1pO9uwRI6WoZxqR 0Z6RaBVDXAXb3kDFeXh3fP1hZL2bdzL5KjHUm5bggMywBLJJ9Jb+hPfmKH04Q5kMIbUw Eyq+ZsSLn73PcqRAXgfSkx7mwv6xl5ro/qccEXC0CVUOaj6c/EQy8xJ+Wv694bqrXC8s bF17vybChBzDNXV4F0sEhAO4jHK3fMkUrhqTi5ViKzIOSJ6U3nkbPawKkEbWsdP9oLxM M3bBk2WHO5iWWHvtP/s9cvbeHBEIFMs9et2ObzzhahkU/X6iZ02hv4tDJI1mn74V3rGz KTIw== X-Gm-Message-State: AOAM531/2ZXWdD+3YsjV2sRY6PFI2sKZAO5kd5vKGGXJ3CzdTLps43f8 mQkXj6lYL4r/jasKtwolAF13wcfe6TLEtzrY6Uc= X-Google-Smtp-Source: ABdhPJxHWY3YYf7E4ssc7BG59Xe9mPWshRcDa2IS/0fi1MiGaCNL8O2JDnmyd35cPnb+xMgZIQ9zwdiwKRWRghIOsoo= X-Received: by 2002:a17:906:f841:: with SMTP id ks1mr1855372ejb.507.1611877688626; Thu, 28 Jan 2021 15:48:08 -0800 (PST) MIME-Version: 1.0 References: <20210127233345.339910-1-shy828301@gmail.com> <20210127233345.339910-7-shy828301@gmail.com> In-Reply-To: From: Yang Shi Date: Thu, 28 Jan 2021 15:47:57 -0800 Message-ID: Subject: Re: [v5 PATCH 06/11] mm: vmscan: use a new flag to indicate shrinker is registered To: Vlastimil Babka Cc: Roman Gushchin , Kirill Tkhai , Shakeel Butt , Dave Chinner , Johannes Weiner , Michal Hocko , Andrew Morton , Linux MM , Linux FS-devel Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 28, 2021 at 9:56 AM Vlastimil Babka wrote: > > On 1/28/21 12:33 AM, Yang Shi wrote: > > Currently registered shrinker is indicated by non-NULL shrinker->nr_deferred. > > This approach is fine with nr_deferred at the shrinker level, but the following > > patches will move MEMCG_AWARE shrinkers' nr_deferred to memcg level, so their > > shrinker->nr_deferred would always be NULL. This would prevent the shrinkers > > from unregistering correctly. > > > > Remove SHRINKER_REGISTERING since we could check if shrinker is registered > > successfully by the new flag. > > > > Signed-off-by: Yang Shi > > --- > > include/linux/shrinker.h | 7 ++++--- > > mm/vmscan.c | 27 +++++++++------------------ > > 2 files changed, 13 insertions(+), 21 deletions(-) > > > > diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h > > index 0f80123650e2..1eac79ce57d4 100644 > > --- a/include/linux/shrinker.h > > +++ b/include/linux/shrinker.h > > @@ -79,13 +79,14 @@ struct shrinker { > > #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ > > > > /* Flags */ > > -#define SHRINKER_NUMA_AWARE (1 << 0) > > -#define SHRINKER_MEMCG_AWARE (1 << 1) > > +#define SHRINKER_REGISTERED (1 << 0) > > +#define SHRINKER_NUMA_AWARE (1 << 1) > > +#define SHRINKER_MEMCG_AWARE (1 << 2) > > /* > > * It just makes sense when the shrinker is also MEMCG_AWARE for now, > > * non-MEMCG_AWARE shrinker should not have this flag set. > > */ > > -#define SHRINKER_NONSLAB (1 << 2) > > +#define SHRINKER_NONSLAB (1 << 3) > > > > extern int prealloc_shrinker(struct shrinker *shrinker); > > extern void register_shrinker_prepared(struct shrinker *shrinker); > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 92e917033797..256896d157d4 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -308,19 +308,6 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id) > > } > > } > > > > -/* > > - * We allow subsystems to populate their shrinker-related > > - * LRU lists before register_shrinker_prepared() is called > > - * for the shrinker, since we don't want to impose > > - * restrictions on their internal registration order. > > - * In this case shrink_slab_memcg() may find corresponding > > - * bit is set in the shrinkers map. > > - * > > - * This value is used by the function to detect registering > > - * shrinkers and to skip do_shrink_slab() calls for them. > > - */ > > -#define SHRINKER_REGISTERING ((struct shrinker *)~0UL) > > - > > static DEFINE_IDR(shrinker_idr); > > > > static int prealloc_memcg_shrinker(struct shrinker *shrinker) > > @@ -329,7 +316,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) > > > > down_write(&shrinker_rwsem); > > /* This may call shrinker, so it must use down_read_trylock() */ > > - id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL); > > + id = idr_alloc(&shrinker_idr, NULL, 0, 0, GFP_KERNEL); > > Is it still needed to register a NULL and then replace it with real pointer, > given the SHRINKER_REGISTERED flag? Good question. Should not need this alloc-replace sequence anymore. The shrinker_slab_memcg() should see SHRINKER_REGISTERED set when the shrinker is really registered since the registration is protected by write shrinker_rwsem. Will fix this in v6. > > > if (id < 0) > > goto unlock; > > > > @@ -496,6 +483,7 @@ void register_shrinker_prepared(struct shrinker *shrinker) > > if (shrinker->flags & SHRINKER_MEMCG_AWARE) > > idr_replace(&shrinker_idr, shrinker, shrinker->id); > > #endif > > + shrinker->flags |= SHRINKER_REGISTERED; > > up_write(&shrinker_rwsem); > > } > > > > @@ -515,13 +503,16 @@ EXPORT_SYMBOL(register_shrinker); > > */ > > void unregister_shrinker(struct shrinker *shrinker) > > { > > - if (!shrinker->nr_deferred) > > + if (!(shrinker->flags & SHRINKER_REGISTERED)) > > return; > > - if (shrinker->flags & SHRINKER_MEMCG_AWARE) > > - unregister_memcg_shrinker(shrinker); > > + > > down_write(&shrinker_rwsem); > > list_del(&shrinker->list); > > + shrinker->flags &= ~SHRINKER_REGISTERED; > > up_write(&shrinker_rwsem); > > + > > + if (shrinker->flags & SHRINKER_MEMCG_AWARE) > > + unregister_memcg_shrinker(shrinker); > > kfree(shrinker->nr_deferred); > > shrinker->nr_deferred = NULL; > > } > > @@ -687,7 +678,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, > > struct shrinker *shrinker; > > > > shrinker = idr_find(&shrinker_idr, i); > > - if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) { > > + if (unlikely(!shrinker || !(shrinker->flags & SHRINKER_REGISTERED))) { > > if (!shrinker) > > clear_bit(i, info->map); > > continue; > > >