From nobody Fri Sep 02 12:05:37 2022 X-Original-To: freebsd-current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4MJxSh5pKZz4bsjg for ; Fri, 2 Sep 2022 12:05:40 +0000 (UTC) (envelope-from mjguzik@gmail.com) Received: from mail-lj1-x22c.google.com (mail-lj1-x22c.google.com [IPv6:2a00:1450:4864:20::22c]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1D4" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4MJxSh0cx2z42sR for ; Fri, 2 Sep 2022 12:05:40 +0000 (UTC) (envelope-from mjguzik@gmail.com) Received: by mail-lj1-x22c.google.com with SMTP id z20so2047950ljq.3 for ; Fri, 02 Sep 2022 05:05:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:subject:message-id:date:from:mime-version:from:to:cc:subject :date; bh=bh+DR1bX4qi7vDCTGYx7+DVgEWjGuD8q49OxjnLJzTU=; b=UngdU7hd+UFnzADM2XHD0OMZAQjd8CohlbEAG0ZIAAoWb4sBVvaTQZO5E1agzcbnvp d/7KEHz+ozm2ITjbHDApbON0Y1HPmhaTD+FMOagKvgVWbqYA7g7I/DwazoSaJnA7inKY 7E9l5FqjFyjzDvNQ+WR1I1dG0WOOBxC8cEYpie2ygy0+tdu7QYGtrnG7BjHqe15tBmyQ tR/UCjSOTcSkAqPcr9qoQAQo625MkuuSBIzM4iA4mfJjbEYOEV6dhcu0kxV7sp88B/wV 9180tDU4A8qlTBc2eYW3IOImHwOM6W4exOkqdpcqnCjyCqU8xpUWwQHiMZw2JNW7hEak w8Iw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:subject:message-id:date:from:mime-version:x-gm-message-state :from:to:cc:subject:date; bh=bh+DR1bX4qi7vDCTGYx7+DVgEWjGuD8q49OxjnLJzTU=; b=z7HLJOIbWvhJGDmmrxxY+CUc6CpM6yiOAt/VZMxBaRcTa5DfDWUpqnZJI42UoMrVWq 5wqOrfU31NUCgz2pdnOFQtjbNU3m1FdVMj7dSiI4MdWudxcXsSd/539tpfB3FyXLZtPO XPxJJtgRTA4JoA5I3T+t2qqohKe5oBW0rBLpw7UuSEo6B2dgeUZ7UCJIETYKdobllipi 8Z+mN7RNFDkgWldtQ1eWA5lhf/jPieJ3p9xuACq5fBjPw2bDHiLfI5Ef5TD0eAQcZYjX H3WWcvUPlU0PCkgFaLVLfeNFW+mhxIwuf+wM5zDOW9M7LunP1hWG/amMkpBooZF6PE58 H2nA== X-Gm-Message-State: ACgBeo3LUhT4GA+Jx/tdS1ErjefinZ3gvrebelUCtU9Ha6LhYAIncYp+ UHTrnugr7/hLsNYj5bGhhtfh4Y9tHaT1GzgQXcIka+Jh X-Google-Smtp-Source: AA6agR7mSJN/8/PJ7XJUDDfwB6Z2Ld60N0DNekeil13IsILT9wDuZ01fc3uIE3UD1pwKtIm/cD8AgBaD26z3IC3/ccY= X-Received: by 2002:a2e:bc06:0:b0:266:23b7:283d with SMTP id b6-20020a2ebc06000000b0026623b7283dmr6535600ljf.151.1662120337716; Fri, 02 Sep 2022 05:05:37 -0700 (PDT) List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@freebsd.org MIME-Version: 1.0 Received: by 2002:a05:6520:14d:b0:211:6cae:be17 with HTTP; Fri, 2 Sep 2022 05:05:37 -0700 (PDT) From: Mateusz Guzik Date: Fri, 2 Sep 2022 14:05:37 +0200 Message-ID: Subject: kernel-side thread stack swapping To: freebsd-current@freebsd.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 4MJxSh0cx2z42sR X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20210112 header.b=UngdU7hd; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of mjguzik@gmail.com designates 2a00:1450:4864:20::22c as permitted sender) smtp.mailfrom=mjguzik@gmail.com X-Spamd-Result: default: False [-3.00 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-0.998]; NEURAL_HAM_SHORT(-1.00)[-0.998]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20210112]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36:c]; MIME_GOOD(-0.10)[text/plain]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::22c:from]; MLMMJ_DEST(0.00)[freebsd-current@freebsd.org]; FROM_EQ_ENVFROM(0.00)[]; ARC_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; DKIM_TRACE(0.00)[gmail.com:+]; MID_RHS_MATCH_FROMTLD(0.00)[]; RCVD_TLS_LAST(0.00)[]; FREEMAIL_FROM(0.00)[gmail.com]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-current@freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; TO_DN_NONE(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim] X-ThisMailContainsUnwantedMimeParts: N Is this really of practical use today? I have a WIP patch which needs to temporarily store something on the stack and should things go wrong enough it will be accessed by UMA, which can't handle the fault nor decide to skip the access. I can add something like td_pinstack or whatever to keep it around, but perhaps the entire machinery can be just whacked? -- Mateusz Guzik