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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2EEC2C54E58 for ; Tue, 12 Mar 2024 16:53:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B9C8B8D0065; Tue, 12 Mar 2024 12:53:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B4CA38D0017; Tue, 12 Mar 2024 12:53:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A145E8D0065; Tue, 12 Mar 2024 12:53:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 9214D8D0017 for ; Tue, 12 Mar 2024 12:53:57 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 5039A80702 for ; Tue, 12 Mar 2024 16:53:57 +0000 (UTC) X-FDA: 81888984114.17.BB51817 Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) by imf25.hostedemail.com (Postfix) with ESMTP id AF98DA001E for ; Tue, 12 Mar 2024 16:53:55 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=soleen-com.20230601.gappssmtp.com header.s=20230601 header.b=HvFfgTg8; dmarc=pass (policy=none) header.from=soleen.com; spf=pass (imf25.hostedemail.com: domain of pasha.tatashin@soleen.com designates 209.85.160.169 as permitted sender) smtp.mailfrom=pasha.tatashin@soleen.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1710262435; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=CAMusPdvz5a8W0RgIatIFRN14xcgJUxEx/bPUCmYvZI=; b=j26nT719KFDxZdNwLiLKviXQdYoECtzCx0tYZh0x0qpLvvvWePYJ8Oc7jkOG+2xgXEwqU+ QKChizAUEx/v/X+don8j3w39BElDvh+nsCHEh/fdpH3ZD15JygQZMSKG8yM89CjkI4+NP+ Myvw07tE1ec3kqNKFT+o9akAZiSdwHM= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=soleen-com.20230601.gappssmtp.com header.s=20230601 header.b=HvFfgTg8; dmarc=pass (policy=none) header.from=soleen.com; spf=pass (imf25.hostedemail.com: domain of pasha.tatashin@soleen.com designates 209.85.160.169 as permitted sender) smtp.mailfrom=pasha.tatashin@soleen.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1710262435; a=rsa-sha256; cv=none; b=iMoPHqPCUh939rKCuXuLyHlIIbqXShpui7aOlQVeamDdONqw+kAg0yqKVJnfh/YVWH2ldM 0kjFgCR5x5qtSBYqlzla42BfoWsPN5QCEy/jR69nxbThQlIdwwvLUb8A06AVYqAtJvtngh IlIaMLbD6mdqWHfp7hxksmQCoGhHsuA= Received: by mail-qt1-f169.google.com with SMTP id d75a77b69052e-42f2009e559so418211cf.0 for ; Tue, 12 Mar 2024 09:53:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen-com.20230601.gappssmtp.com; s=20230601; t=1710262435; x=1710867235; darn=kvack.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=CAMusPdvz5a8W0RgIatIFRN14xcgJUxEx/bPUCmYvZI=; b=HvFfgTg8aPpVKVv7TTPELj1dFpB6RxhAS4uDkExL0KG5OrC0Q0ynGmX0OcsQZwR+JV Kuh74WNkgeRUmzVs0cUYX7++6iG+tvAK6hvTgyF/DK0ewZs7GsvfiiiFD3qhyoaSmniN iBzEgURW8CyHwvmsvPfiu8aS6BVbuq+NC7VO+SJT3Ipu9puOGkPI4E9bUdD1yEnE2qap Uv32VTAPTsubSJNBfs6NVD1wn8rrhcvSfKMLt8icYlJ0PkY4Mw3Q6tnNcO5NNy9Z7qnR WMYGQjP4EehjWGh+Uk+bT2uHLF8FP7K4Tosfzn/pvjctFtuGpOYQSBuTwbJAXujq6Fqb y0Hw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1710262435; x=1710867235; 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=CAMusPdvz5a8W0RgIatIFRN14xcgJUxEx/bPUCmYvZI=; b=UJHezOaZPNFz1EbyeDa86RCB3X/vKiWXPffGLq2dM/IHU76epOaHUEVQDavrkqJUZk m/UteQLfQe2qWJKBOVD6dOM89Il/1Db3Y1nPzD4G1yA0YgF3ZAVdsRPzsV2qgdhowU62 hGyvdc++xtXT/dAC8Q9xbKJthu3jmslQaKyLGGN+DndhMB19ABth3zzRX8TUDKUdnxL2 VzmUlYVZ8isklr7mTY6yAP6V3ndhp/FmI9qT+WGXWzoFbXZXFZz9YmZqUCPSQOGCMC1w 3T7+V3gz/kWUMmYuayuoaATUS/jFZakkgSRuv8oW6JZS9xj+qYjhbBxm/6LBD66SpGTv aPIw== X-Forwarded-Encrypted: i=1; AJvYcCWcGk7/OQ6Q02JgPwGkOEe8uDMzcbI6a/X20EqrzdzvU8BuHHU3tPxocRqrKNePQ3U7dzb1via5b0gmR+5cdEGMZ8w= X-Gm-Message-State: AOJu0Ywf5cnjA2ivIhd2MMSggBIbeqWlFgw9b/UOpt1QiiiEbcAaOqRX Mi8fCubAiIdlkWI7b29mEDN0YJ5TpE6VoZFrgAX4yp75WiceRSk1EnZLE4619skF3K0/3Xh3jWr rtxbId4O4IvNUlgP0pJrGRSPCbl819Ytuc0EFSw== X-Google-Smtp-Source: AGHT+IEHJBCriKeLHdESWyjbldGlr/KrnIvjIKeKrARpBoZ5wXfYc8la50wvxNKDwp+NxL7/FwXEt6glvxmRx6CXXYI= X-Received: by 2002:ac8:5bc9:0:b0:42e:bb8c:6344 with SMTP id b9-20020ac85bc9000000b0042ebb8c6344mr214265qtb.9.1710262434782; Tue, 12 Mar 2024 09:53:54 -0700 (PDT) MIME-Version: 1.0 References: <20240311164638.2015063-1-pasha.tatashin@soleen.com> <20240311164638.2015063-7-pasha.tatashin@soleen.com> In-Reply-To: From: Pasha Tatashin Date: Tue, 12 Mar 2024 12:53:16 -0400 Message-ID: Subject: Re: [RFC 06/14] fork: zero vmap stack using clear_page() instead of memset() To: Nikolay Borisov Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, x86@kernel.org, bp@alien8.de, brauner@kernel.org, bristot@redhat.com, bsegall@google.com, dave.hansen@linux.intel.com, dianders@chromium.org, dietmar.eggemann@arm.com, eric.devolder@oracle.com, hca@linux.ibm.com, hch@infradead.org, hpa@zytor.com, jacob.jun.pan@linux.intel.com, jgg@ziepe.ca, jpoimboe@kernel.org, jroedel@suse.de, juri.lelli@redhat.com, kent.overstreet@linux.dev, kinseyho@google.com, kirill.shutemov@linux.intel.com, lstoakes@gmail.com, luto@kernel.org, mgorman@suse.de, mic@digikod.net, michael.christie@oracle.com, mingo@redhat.com, mjguzik@gmail.com, mst@redhat.com, npiggin@gmail.com, peterz@infradead.org, pmladek@suse.com, rick.p.edgecombe@intel.com, rostedt@goodmis.org, surenb@google.com, tglx@linutronix.de, urezki@gmail.com, vincent.guittot@linaro.org, vschneid@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: AF98DA001E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: awppshzjmeufsr8qdz548f19pxdyparr X-HE-Tag: 1710262435-289285 X-HE-Meta: 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 lhKhSzmO dFd/UPY1jC2UqM+VH98AZfhbAUDpimlI/buCaHr3IG3vx1UeD2ilKfqdJ+lE9NG+GByc5RakBAof2CRT6CuyCYiqz85me8QT8zdsb 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: List-Subscribe: List-Unsubscribe: On Tue, Mar 12, 2024 at 3:16=E2=80=AFAM Nikolay Borisov wrote: > > > > On 11.03.24 =D0=B3. 18:46 =D1=87., Pasha Tatashin wrote: > > In preporation for dynamic kernel stacks do not zero the whole span of > > the stack, but instead only the pages that are part of the vm_area. > > > > This is because with dynamic stacks we might have only partially > > populated stacks. > > > > Signed-off-by: Pasha Tatashin > > --- > > kernel/fork.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/fork.c b/kernel/fork.c > > index 6a2f2c85e09f..41e0baee79d2 100644 > > --- a/kernel/fork.c > > +++ b/kernel/fork.c > > @@ -263,8 +263,8 @@ static int memcg_charge_kernel_stack(struct vm_stru= ct *vm) > > static int alloc_thread_stack_node(struct task_struct *tsk, int node) > > { > > struct vm_struct *vm_area; > > + int i, j, nr_pages; > > void *stack; > > - int i; > > > > for (i =3D 0; i < NR_CACHED_STACKS; i++) { > > vm_area =3D this_cpu_xchg(cached_stacks[i], NULL); > > @@ -282,7 +282,9 @@ static int alloc_thread_stack_node(struct task_stru= ct *tsk, int node) > > stack =3D kasan_reset_tag(vm_area->addr); > > > > /* Clear stale pointers from reused stack. */ > > - memset(stack, 0, THREAD_SIZE); > > + nr_pages =3D vm_area->nr_pages; > > + for (j =3D 0; j < nr_pages; j++) > > + clear_page(page_address(vm_area->pages[j])); > > Can't this be memset(stack, 0, nr_pages*PAGE_SIZE) ? No, we can't, because the pages can be physically discontiguous. Pasha