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 DF196C54E71 for ; Tue, 19 Mar 2024 20:09:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 58B516B0088; Tue, 19 Mar 2024 16:09:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 53B5A6B0089; Tue, 19 Mar 2024 16:09:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3DC8A6B008A; Tue, 19 Mar 2024 16:09:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 2F0AB6B0088 for ; Tue, 19 Mar 2024 16:09:09 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id CA1688028F for ; Tue, 19 Mar 2024 20:09:08 +0000 (UTC) X-FDA: 81914877576.14.BC18CA3 Received: from mail-ej1-f46.google.com (mail-ej1-f46.google.com [209.85.218.46]) by imf06.hostedemail.com (Postfix) with ESMTP id 04C1A180008 for ; Tue, 19 Mar 2024 20:09:06 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=DTOGFGe4; spf=pass (imf06.hostedemail.com: domain of yosryahmed@google.com designates 209.85.218.46 as permitted sender) smtp.mailfrom=yosryahmed@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1710878947; 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=HwfgyBIzjXd0CLtWmjCy0jIs1nMeq6X0wQLJWRmd4lk=; b=Wpt11awxlYKCvfVPbruQYKk2OlTOyXiNltXuc4937Ii9uq0ouEKjXH/kKxMgRM5klX3GvV 8UgXSqLAuwqLvcUEZUOGVs4A7z8er3x9wMF8E8xjV0mu3ptVgWmQ7XEg+0gJHdeAo0kQ/i s0F+D9cyaiT7N1uZq8bAzQEoSTCnUqs= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1710878947; a=rsa-sha256; cv=none; b=3uyY+uoT9ftFowICpNtiOvw7QtmODE/cmVImfEv6T7yyI3BK0yGR3+2BfICFxnLIb16NM8 zXQKNqnRU4Alcd68JIGgMEpfUMV/u65hWbRPV+XugtNkeSRVNECm14zBGOOFgE0m3yAmGg 3FNbda0rkuVxUFe7brWVdktfUurAh0Y= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=DTOGFGe4; spf=pass (imf06.hostedemail.com: domain of yosryahmed@google.com designates 209.85.218.46 as permitted sender) smtp.mailfrom=yosryahmed@google.com; dmarc=pass (policy=reject) header.from=google.com Received: by mail-ej1-f46.google.com with SMTP id a640c23a62f3a-a46ba1a05e0so368780866b.3 for ; Tue, 19 Mar 2024 13:09:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1710878945; x=1711483745; 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=HwfgyBIzjXd0CLtWmjCy0jIs1nMeq6X0wQLJWRmd4lk=; b=DTOGFGe4Ab3G2NLbvsP10w4rTUdVKtYlmODjt209NjiKGZL4tN8MvY08Udlx0kk1e4 bxKHw0nqTJp0yEanK9Fe20dc8Sz+vp2JJL/kHQ3DKZHd+slRrjHNoVCHPhD9w9vwDISW /bzvJk7JRlgrVNe2v4pvSwAxnLrmCv3+BFHAFKoQ8L+dXZyc+xquaVCe7WUjEP1u4TIk rTWz2raBOFo2ccqldu2BoSzC/PJAFOZuJ26MuJb3qnP8ukO7B9tpNJpbDJ+AVE/AVGJW dwZkC8YnBUDVMS2pItokrHhgFYOoQvQpbd1T9McH0Aih22errqDI0CjmPeG2l+jYKW8o AeNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1710878945; x=1711483745; 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=HwfgyBIzjXd0CLtWmjCy0jIs1nMeq6X0wQLJWRmd4lk=; b=xHIgdx3Ec6jYo3faF7mMuyqsBhRwyS++02lAyho6w7jmxqU0C0rk/bhY7dR719Ve+C w33kx7fxc25Uy8HTGvcMoTPdpSLna9xpofXv4yZwhQEzyY0OdoUz/uaZHFWwJ2dZQ4rh wkrG+eYeWLGGaxDcDpajYaYytyzOHlipFAno16TjIPdnnNj9BDQE+rd9eFuu7vZcJQ0Z H745zn598iD77dQZB9KFJqrYdS0BCqOI5W3Zny8UUH2fd7nL11alJuASnv5ltKkzujOM 7HCt/5XqYzuiEnEXyg8hUfpFs0zD7waaVYxjGaOumwaFzQ5UnQPeyonqadCMbsKuPy0U QHmw== X-Gm-Message-State: AOJu0YzOqV8r8fAVZQGMOmh5b4lPZuhy+BAJXQPuFQ+3Kky5MRSk0ZaV hHJ1yyajKZOL8TlyWUQ74S9khpp/tPFt5AIv+ePObNBDi8PlnBfRLKEaw+p/U9Kdfad2nKymqi4 cA1XjAusqzkpqVKnIC/0pYAjLy7bz9eHMpqVY X-Google-Smtp-Source: AGHT+IHcVNlW/4L9ZJSX+w0WIeNkV/d9UqRMZ7mkUjxPj4cCE/k/HU4FvxUq0OXNwVJOULhDDu4CaV3pI4La9qhMz+4= X-Received: by 2002:a17:906:3e07:b0:a46:8d30:b91c with SMTP id k7-20020a1709063e0700b00a468d30b91cmr2101884eji.34.1710878945094; Tue, 19 Mar 2024 13:09:05 -0700 (PDT) MIME-Version: 1.0 References: <20240311194346.2291333-1-yosryahmed@google.com> In-Reply-To: <20240311194346.2291333-1-yosryahmed@google.com> From: Yosry Ahmed Date: Tue, 19 Mar 2024 13:08:26 -0700 Message-ID: Subject: Re: [PATCH] percpu: clean up all mappings when pcpu_map_pages() fails To: Dennis Zhou , Tejun Heo , Christoph Lameter , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: y7n54dthiajir6awfbawfjgb9o9fm6dm X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 04C1A180008 X-Rspam-User: X-HE-Tag: 1710878946-804258 X-HE-Meta: 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 h/5YyRI4 P9s91+N0n0Gz9aa3v+9oVxbj+5MP+uRhuBa9PFrvTlFeuw8mALkGHIifG/yIesoHnIEnIGLRx7WRv5zASkHP6KtsezDV1DslzuZvOuy4eZeNB3Oi2cRwVed1vM6UTGX4uXubFXt5vpF3oL2a2am2KaG/VOoubUJsJO/sHonn07QCWSI55zVJVXCgxYhx7aHPGbQmi51+I+XKJsj3rovPiGp4FRgZs0Pch7hm1cseB3cLox5h9i/dx5wX35e7F21ZS8myPZVzCRmISj6xrt3eLHF7MPn0elqmWa/O2 X-Bogosity: Ham, tests=bogofilter, spamicity=0.015019, 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 Mon, Mar 11, 2024 at 12:43=E2=80=AFPM Yosry Ahmed wrote: > > In pcpu_map_pages(), if __pcpu_map_pages() fails on a CPU, we call > __pcpu_unmap_pages() to clean up mappings on all CPUs where mappings > were created, but not on the CPU where __pcpu_map_pages() fails. > > __pcpu_map_pages() and __pcpu_unmap_pages() are wrappers around > vmap_pages_range_noflush() and vunmap_range_noflush(). All other callers > of vmap_pages_range_noflush() call vunmap_range_noflush() when mapping > fails, except pcpu_map_pages(). The reason could be that partial > mappings may be left behind from a failed mapping attempt. > > Call __pcpu_unmap_pages() for the failed CPU as well in > pcpu_map_pages(). > > This was found by code inspection, no failures or bugs were observed. > > Signed-off-by: Yosry Ahmed Any thoughts about this change? Should I resend next week after the merge window? > --- > > Perhaps the reason __pcpu_unmap_pages() is not currently being called > for the failed CPU is that the size and alignment requirements make sure > we never leave any partial mappings behind? I have no idea. Nonetheless, > I think we want this change as that could be fragile, and is > inconsistent with other callers. > > --- > mm/percpu-vm.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c > index 2054c9213c433..cd69caf6aa8d8 100644 > --- a/mm/percpu-vm.c > +++ b/mm/percpu-vm.c > @@ -231,10 +231,10 @@ static int pcpu_map_pages(struct pcpu_chunk *chunk, > return 0; > err: > for_each_possible_cpu(tcpu) { > - if (tcpu =3D=3D cpu) > - break; > __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_star= t), > page_end - page_start); > + if (tcpu =3D=3D cpu) > + break; > } > pcpu_post_unmap_tlb_flush(chunk, page_start, page_end); > return err; > -- > 2.44.0.278.ge034bb2e1d-goog >