From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ua1-f46.google.com (mail-ua1-f46.google.com [209.85.222.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B053B7081D for ; Sat, 26 Oct 2024 03:56:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729914979; cv=none; b=bKpBznR1kL6z3KQ29iq8zWhv53l4Uq5Dw35BFXYaw9yr2FcDU8aoIItCtGJZ7oI9aRsPm1wRDMODN7lgs1flPM9wtHPNLc5HqALFf/fnOwGebvUjxKhOG0Ynjbzq48zeOm2zAutoxhSeVjM+gSOtCatKbnG0TlC7jGPsM1OVxlg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729914979; c=relaxed/simple; bh=3oM9WEdtQNIO693hFjB/zmcwWdvOBl5ifNMyfJw9/PE=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=Y3ekhOMaqGyszSi/p8UzE899Yd3EOOVP/5jvhJMY+Fxr+S2cZpeLsv2y6gato+Ha3IMBq472tANvXvhtmGVlKhzxneo11kXZk2h+ygl9gTybV5a1pTVXF7t5x1tuoxijPYdH2/ttsQkcG7IHppeQM+oqGjZ4KCfq0zsmsbQrj4w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=aj7zOPKk; arc=none smtp.client-ip=209.85.222.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aj7zOPKk" Received: by mail-ua1-f46.google.com with SMTP id a1e0cc1a2514c-84fd01c9defso854021241.0 for ; Fri, 25 Oct 2024 20:56:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1729914975; x=1730519775; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=0WKjNsNyT0ruYn6UVMVJ1RKIZyXTRYpCy6zMhmlf4JA=; b=aj7zOPKkgQn0mO3ApOxP99muVIOVBXhDjDjRPpbaF/I0axfRacn+npZNNkRs4SEdG4 3+tqU3XspleGZtVhpuzHrFxyMTmzeR++WFu0tD666dB0cHGhU5SaXG0k37dUTfdp0gjQ whDoKCJHisoplt6JN5HiMIEKPkEJ4si8B/NlzkyTCUN7f7EQ1rDe+5tdw8LZjQ7vMlV5 /ukv9yf1odGDGJup++SpOs1A8rG87PYFqZVYXVOj6mh10Fju1dkgObA79JKAfzwsGDrr fjL8VecpGCbfg4Mcur9ihlnr/qKLLrVkGxtgcqzIlkH7niINDZSGBRZFkNLn8c6KpNXh QJ5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729914975; x=1730519775; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=0WKjNsNyT0ruYn6UVMVJ1RKIZyXTRYpCy6zMhmlf4JA=; b=L2USRnJDdPnY++tV+CXV0HlItMBbADdmcirGAQhS1Ns/WgTTWRovaPFCd3CRFx1NdJ V/FJSa4Mf1MEdYCwjxK/+FNuKzNPYtJvYfJanESnE3Lz4q/PKdCfVKt2WRPZsaI9X6NI mmjw9oxsX5JT08qcYVwm03dRS19uEiWDrbBZwTXKm03CZvAqsXYIZQpeEyWx9u7/w1QU Gpfi5LCxRKWQtVOA3pVxKnWh4HNuK+PzXY3QbdX3maYoSO3GRkcVLSViIMLC1uq5+OVg pw3FYu9NUnd+UOujwt9RKWzPSXHZlGO2ZIfQbRwb/m89txQCq5u+oHNcZeDpz0fx/JkT 1FWg== X-Forwarded-Encrypted: i=1; AJvYcCVnC3IeuFV7I0nkEm1R5xh3AfDIlVwcD34jCPIpR0AzTy2wwZCz+3EjBXPuC3HZGBBDZ2+eJBcXUg/ABcLH@vger.kernel.org X-Gm-Message-State: AOJu0YzB7UVRJlfe4t3T9+tdXnVkUI8xfknayxK7cjRJh2bRPUo//BVh d1nLZPRF0te6J79Bw/uEEVzsoonmVBFxVCOk+yjFnb9VsZZoevqmhuuY5dvVwusP+chiV0yc/pO BfUKR+DvXLqU3NPdDR4eNVVItZz/+9ScJGvbf X-Google-Smtp-Source: AGHT+IGHNioCV05B550z2HqdgbUh0S/Q4eiZK4coivQy8ntPYu+GO8YLiwCo3H1KXVMRJGwT6JD11juuGsuy611LTeQ= X-Received: by 2002:a05:6102:32d2:b0:4a4:7980:b9c7 with SMTP id ada2fe7eead31-4a8cfb83109mr1334887137.14.1729914975276; Fri, 25 Oct 2024 20:56:15 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241025012304.2473312-1-shakeel.butt@linux.dev> <20241025012304.2473312-6-shakeel.butt@linux.dev> In-Reply-To: <20241025012304.2473312-6-shakeel.butt@linux.dev> From: Yu Zhao Date: Fri, 25 Oct 2024 21:55:38 -0600 Message-ID: Subject: Re: [PATCH v1 5/6] memcg-v1: no need for memcg locking for MGLRU To: Shakeel Butt Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Hugh Dickins , Yosry Ahmed , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, Meta kernel team Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, Oct 24, 2024 at 7:23=E2=80=AFPM Shakeel Butt wrote: > > While updating the generation of the folios, MGLRU requires that the > folio's memcg association remains stable. With the charge migration > deprecated, there is no need for MGLRU to acquire locks to keep the > folio and memcg association stable. > > Signed-off-by: Shakeel Butt > --- > mm/vmscan.c | 11 ----------- > 1 file changed, 11 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 29c098790b01..fd7171658b63 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3662,10 +3662,6 @@ static void walk_mm(struct mm_struct *mm, struct l= ru_gen_mm_walk *walk) > if (walk->seq !=3D max_seq) > break; Please remove the lingering `struct mem_cgroup *memcg` as well as folio_memcg_rcu(). Otherwise it causes both build and lockdep warnings. > - /* folio_update_gen() requires stable folio_memcg() */ > - if (!mem_cgroup_trylock_pages(memcg)) > - break; > - > /* the caller might be holding the lock for write */ > if (mmap_read_trylock(mm)) { > err =3D walk_page_range(mm, walk->next_addr, ULON= G_MAX, &mm_walk_ops, walk); > @@ -3673,8 +3669,6 @@ static void walk_mm(struct mm_struct *mm, struct lr= u_gen_mm_walk *walk) > mmap_read_unlock(mm); > } > > - mem_cgroup_unlock_pages(); > - > if (walk->batched) { > spin_lock_irq(&lruvec->lru_lock); > reset_batch_size(walk); > @@ -4096,10 +4090,6 @@ bool lru_gen_look_around(struct page_vma_mapped_wa= lk *pvmw) > } > } > > - /* folio_update_gen() requires stable folio_memcg() */ > - if (!mem_cgroup_trylock_pages(memcg)) > - return true; > - > arch_enter_lazy_mmu_mode(); > > pte -=3D (addr - start) / PAGE_SIZE; > @@ -4144,7 +4134,6 @@ bool lru_gen_look_around(struct page_vma_mapped_wal= k *pvmw) > } > > arch_leave_lazy_mmu_mode(); > - mem_cgroup_unlock_pages(); > > /* feedback from rmap walkers to page table walkers */ > if (mm_state && suitable_to_scan(i, young)) > -- > 2.43.5 > >