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 2D279EE4993 for ; Sun, 20 Aug 2023 12:48:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A9C508E0005; Sun, 20 Aug 2023 08:48:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A4CCA8D0002; Sun, 20 Aug 2023 08:48:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9150F8E0005; Sun, 20 Aug 2023 08:48:04 -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 802AA8D0002 for ; Sun, 20 Aug 2023 08:48:04 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 50E8C1A01CE for ; Sun, 20 Aug 2023 12:48:04 +0000 (UTC) X-FDA: 81144460488.20.DC2380D Received: from mail-lf1-f49.google.com (mail-lf1-f49.google.com [209.85.167.49]) by imf24.hostedemail.com (Postfix) with ESMTP id 540DE18001A for ; Sun, 20 Aug 2023 12:48:02 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=fcrxMHYM; dmarc=none; spf=pass (imf24.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.167.49 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1692535682; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=EAlwOLhvodbStS7U0JzC0JNPjiXvdKGT5YChhjDmGgM=; b=6IpbXexMkyomiGJZfZSCFANf5sNuhfTwJmYRhtAaXSOgEPlTRwEAurtlSx2DjRimoFnQSt Qx468LqgInqYtnE0N0raCbnGWTlmO/4MEuUCbX7XdxmE5FgPIlUSqudUowmSpu4oEaGUI+ Xz7pNXl4thLE3iWTqDISqDaqmVsTYik= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=fcrxMHYM; dmarc=none; spf=pass (imf24.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.167.49 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1692535682; a=rsa-sha256; cv=none; b=70ywTSKdX0UF2G9Ny4pf9S7mhxgE8rWQMv6ItUga5c54xzlEbhFGFkyDCiiQsOMJ50PyVM Cm+nRKv7jJk7k5IXdsyaALff2Tnv+PqQrSNZyJVyY8tn5WbedgdDRuLl4OhorVuMeXG2os WDNqueDkcsXlMUmRQvpnjQdMKDT7FkE= Received: by mail-lf1-f49.google.com with SMTP id 2adb3069b0e04-4ff8f2630e3so3827063e87.1 for ; Sun, 20 Aug 2023 05:48:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; t=1692535680; x=1693140480; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=EAlwOLhvodbStS7U0JzC0JNPjiXvdKGT5YChhjDmGgM=; b=fcrxMHYMQRMMra3W/WCtJSpdf4cqQDbWjkFWZNS5ya4UaRHBr/TL5DWgBcJm+30xPx 9w5s7glsbYt/2o2CZojejJX1w7QwgvwuaGx8b3GvGt2jvuk5KUmkMwo4vA0KP+VauUkS ZUR17eHag0ypEtHOc3LLps9EOa2HGJH6ZJaIY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692535680; x=1693140480; h=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=EAlwOLhvodbStS7U0JzC0JNPjiXvdKGT5YChhjDmGgM=; b=QHTxDMc52vJ8G2FZHiaXnQp/UWXaMnq8HUEZzEbBcZVvtO8VpY/g4JOo2it+4AD5Cm XyKePhZnZNjumEl7C3Xo8yARdW25jxvz2b8HlWtiU+bUJ6TvPAPiNGQLe7rJHJ2Yy58N AY9YwSaTlgAaXRk4uaoUlQjRwiR0mudAIw5VIZpRVny7izln7XkdImNTM6S0FdSIFiCx isfrCtURZFR3th0cRV47mWx4PpXq60evVfJBkw7q5oiJiQk9zvGrfwKCz05+Pp9esH+x 9uiDl63nGM2F3cWEATeginLJbrwb71xsPHwm9uGqk2rrUf0SbLvUqznUZU7erJABgURz mt1w== X-Gm-Message-State: AOJu0YzcuEHIGNoF/7u+6lOtyqoVCe2XZtpgEnEJkrubs6koIMkZUVXW ELSkeB+wkne/6ZFeocXwudJHeWp0rgmY4Z6/1RMZS8MM X-Google-Smtp-Source: AGHT+IGvYAXoJJlH1rVIpLajRn9nN+DJfbQvoYyn2oE3SzeHvXCdV+CS060gbnE26agr8CgA770dOg== X-Received: by 2002:a05:6512:10d5:b0:4fe:2ac1:4151 with SMTP id k21-20020a05651210d500b004fe2ac14151mr2633924lfg.63.1692535680252; Sun, 20 Aug 2023 05:48:00 -0700 (PDT) Received: from mail-ed1-f45.google.com (mail-ed1-f45.google.com. [209.85.208.45]) by smtp.gmail.com with ESMTPSA id i12-20020a1709061ccc00b00991e2b5a27dsm4587967ejh.37.2023.08.20.05.47.59 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 20 Aug 2023 05:47:59 -0700 (PDT) Received: by mail-ed1-f45.google.com with SMTP id 4fb4d7f45d1cf-51e2a6a3768so3181089a12.0 for ; Sun, 20 Aug 2023 05:47:59 -0700 (PDT) X-Received: by 2002:aa7:d996:0:b0:522:d6f4:c0eb with SMTP id u22-20020aa7d996000000b00522d6f4c0ebmr2577796eds.40.1692535679006; Sun, 20 Aug 2023 05:47:59 -0700 (PDT) MIME-Version: 1.0 References: <20230820104303.2083444-1-mjguzik@gmail.com> In-Reply-To: From: Linus Torvalds Date: Sun, 20 Aug 2023 14:47:41 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mm: remove unintentional voluntary preemption in get_mmap_lock_carefully To: Mateusz Guzik Cc: Matthew Wilcox , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Stat-Signature: sdwuji4u5y89jc3zr75c5esrhf5fpwz4 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 540DE18001A X-HE-Tag: 1692535682-539024 X-HE-Meta: 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 KM01Y8Zv 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 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 Sun, 20 Aug 2023 at 14:41, Mateusz Guzik wrote: > > On 8/20/23, Matthew Wilcox wrote: > > > > Except now we search the exception tables every time we call it. > > The now-deleted comment (c2508ec5a58d) suggests this is slow: Yeah, that was the intent. But I agree that we should basically avoid trying to sleep just as we got the lock. > My first patch looked like this: Well, that's disgusting and strange. > - might_sleep(); > +#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) > + __might_sleep(__FILE__, __LINE__); > +#endif Why would you have that strange #ifdef? __might_sleep() just goes away without that debug option anyway. But without that odd ifdef, I think it's fine. Linus