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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DB977CCD18E for ; Tue, 14 Oct 2025 19:50:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EB8FD8E00E9; Tue, 14 Oct 2025 15:50:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E694A8E0090; Tue, 14 Oct 2025 15:50:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D580D8E00E9; Tue, 14 Oct 2025 15:50:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id BE62F8E0090 for ; Tue, 14 Oct 2025 15:50:29 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 6A6195C44A for ; Tue, 14 Oct 2025 19:50:29 +0000 (UTC) X-FDA: 83997761778.13.543ED0C Received: from mail-wm1-f42.google.com (mail-wm1-f42.google.com [209.85.128.42]) by imf20.hostedemail.com (Postfix) with ESMTP id 908C31C0005 for ; Tue, 14 Oct 2025 19:50:27 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b="Gj/5RGPe"; spf=pass (imf20.hostedemail.com: domain of dalalitamar@gmail.com designates 209.85.128.42 as permitted sender) smtp.mailfrom=dalalitamar@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1760471427; a=rsa-sha256; cv=none; b=xPz82SGBfBBGCJF2D19PqyZIqdUl9Y7+ICOuODcgS6LbIceWA3TmTyOgLWJHy/wRDFa5ty 9NmlBwr2wCHG6aeeFJRnrvn76sNksX08lHtbN5uVDaIu2A1vDaSXexuesBvtj+6X2zSZ6K eUqHjZR4eDhQtcAHe1dpxqwurWWYxRI= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b="Gj/5RGPe"; spf=pass (imf20.hostedemail.com: domain of dalalitamar@gmail.com designates 209.85.128.42 as permitted sender) smtp.mailfrom=dalalitamar@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1760471427; 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: references:dkim-signature; bh=MkhCJA/dXOXcwZ7S2jDqDvDpKsjxlEMR9YOOSuHW/cQ=; b=Dr9IEBwAIFuxgB/xZWuguTH6+g6NCcK5qVcPur8IzfH+XDWETkBC2LoK/BlrsB9aObj/LI meQVaqJCdhr43W1W0e+NQGZ1sj2DY7Mg2tWujQ8lL8B0t63TXN3U3MsMn9ifkIqj/Tdt1l N0C9IbYMBuKWJGX6zHvVzOTHo70F38M= Received: by mail-wm1-f42.google.com with SMTP id 5b1f17b1804b1-46e37d6c21eso32441135e9.0 for ; Tue, 14 Oct 2025 12:50:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1760471426; x=1761076226; darn=kvack.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=MkhCJA/dXOXcwZ7S2jDqDvDpKsjxlEMR9YOOSuHW/cQ=; b=Gj/5RGPet7du3d4swinUb0E2eilm5N1MlX58CWbcRHN7rOK7MW/8FxYmtlDet4HFYn B73TeK1+w8dcWnJTtgQaPVEQByaPl3ysif0Y6YjtWFykwFC/9qe3y4vTxmA7+5Kgi832 Xwd7FOAIGqjRK7+4ve5ZncaLdlBmT/nN2U/8mhtmvXfZCkPvxHo4F4Tht0B07txzD+FK wb/AMU8SltdG2eMUtz+03jxZ6vW3nCvXiyNfnn+k9ASTV6HujNadIaK5bvsyDVsoOdAj KWP7mhhDmjPqksHJZXS7i6lRa0xiw71J4PeDfN101lPEDBo4DDG8RGzQF7teDh/8S+aW tHtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760471426; x=1761076226; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=MkhCJA/dXOXcwZ7S2jDqDvDpKsjxlEMR9YOOSuHW/cQ=; b=X8W4/kM/N7YirS6MaNYFFhZqG7j5xM94nZtL6ruHmqEjVlyaVdScm9wXZtM3JYf73Q i8MslRbQCQJTL8JD+mBl+OXsfnLilUB3Rh2lgBxgmFHgxgQVe2pTrtvGz+r+zCpoDGmk t3JwjklTLtMfipH0txpcZbrolJ5UYNwh+q+9uiaKwN2PUCL40zzLLEW6bPbXd7Dug4db K20+BxC9W/hWh5b9heqk4xpvhjZN5wwKZmysN2mkllTbrcgOr3lMplGDg1nY+Jow6OuD YGYD3Zg3ggGciKF5+ZyOB1YGKv0rS4BEj1z3BmPCbLDuO63djv8xeJW7QUDEHCwhfCHm LOdw== X-Gm-Message-State: AOJu0YyuhqdYdFrZxNeDqpLc+pa/dDCTbP1DtX7+8fhmr599it5PioZt rSIZg/GX5j2yGlc4mJ86Yw5ji135eSu1o+1nvzdBo/iCt6LIGsi2SanbBx1rIymDm1I= X-Gm-Gg: ASbGncv3xZn+MZunADi7SO0yFQRmWkrDtCGEtmSGW/gjeYK76yFk9UkufVD/dN98flO qysZNxiw0uA5lvkXIiBx106gx8Jy14uUW8hDu1QKJa0NOvKARbPEwn2zOmUhgd79vRmAxCZtfQ1 14zZF0tN5yXGZZx0pWJzBTz9H4JclUW0z4w3qO3uCD6P2xJFPZXAv8Ac8di+hPd6g8Xm9ZXF4u4 LLN0Y/9nipaDSFDJZyRoqzQM2ZtcaPj45PM8IjWuv3xIP5oIBQaZyk+Dxc3d7G1atzfgGOS3CCE O164ob5g3CMkeOWdmuuys3PYQgwn07Zf5Uve3FCd+3um77eFzN2NeCHRV3vGQ7XR9LumdJERJPt gZzFkEAzA2NEynKx1q0nfR+rioixgWlPsNtwQBgy42RRoLW6nMqeEhC1ziPUf9C5h326/Kokx2K xZdnFXi9YnORXd0ZI/O7l3EnN3ZEWhRQ== X-Google-Smtp-Source: AGHT+IHvY3jSRZiPAPUTjqLzv3in2vImFrsh3WPQgcjJugI6dCptqZos5H5Y/+xsV4lVpQrYH25Z3g== X-Received: by 2002:a05:600c:1e86:b0:46e:6a6a:5cf7 with SMTP id 5b1f17b1804b1-46fa9aa0f6dmr179572755e9.12.1760471425371; Tue, 14 Oct 2025 12:50:25 -0700 (PDT) Received: from localhost.localdomain (bzq-79-177-131-159.red.bezeqint.net. [79.177.131.159]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46fb49d03e2sm257969595e9.19.2025.10.14.12.50.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Oct 2025 12:50:23 -0700 (PDT) From: Itamar-Dalal To: linux-mm@kvack.org Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, riel@surriel.com, Liam.Howlett@oracle.com, vbabka@suse.cz, harry.yoo@oracle.com, jannh@google.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org, Itamar-Dalal Subject: [PATCH] =?UTF-8?q?Add=20a=20new=20test=20'migrate.cow=5Fafter=5Ff?= =?UTF-8?q?ork'=20that=20verifies=20correct=20RMAP=20handling=20of=20Copy-?= =?UTF-8?q?On-Write=20pages=20after=20fork().=20Before=20a=20write,=20pare?= =?UTF-8?q?nt=20and=20child=20share=20the=20same=20PFN;=20after=20a=20writ?= =?UTF-8?q?e,=20the=20child=E2=80=99s=20PFN=20differs,=20confirming=20prop?= =?UTF-8?q?er=20COW=20duplication.?= Date: Tue, 14 Oct 2025 22:49:44 +0300 Message-Id: <20251014194944.20341-1-dalalitamar@gmail.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: b6bqip8jchd1ab5hhcecz3dh3fskgxgf X-Rspamd-Queue-Id: 908C31C0005 X-Rspamd-Server: rspam09 X-HE-Tag: 1760471427-422837 X-HE-Meta: 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 5WRbP196 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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: List-Subscribe: List-Unsubscribe: Signed-off-by: Itamar-Dalal --- tools/testing/selftests/mm/rmap.c | 45 ++++++++++++++++++++++++++++++- 1 file changed, 44 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/mm/rmap.c b/tools/testing/selftests/mm/rmap.c index 13f7bccfd0a9..2ba3361fecf0 100644 --- a/tools/testing/selftests/mm/rmap.c +++ b/tools/testing/selftests/mm/rmap.c @@ -430,4 +430,47 @@ TEST_F(migrate, ksm) propagate_children(_metadata, data); } -TEST_HARNESS_MAIN +TEST_F(migrate, cow_after_fork) +{ + struct global_data *data = &self->data; + int status; + pid_t pid; + unsigned long parent_pfn, child_pfn; + int pagemap_fd; + char *region; + + /* Map private anonymous memory and fault it in */ + region = mmap(NULL, data->mapsize, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + ASSERT_NE(region, MAP_FAILED); + memset(region, 0xaa, data->mapsize); + + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); + ASSERT_NE(pagemap_fd, -1); + parent_pfn = pagemap_get_pfn(pagemap_fd, region); + close(pagemap_fd); + + pid = fork(); + ASSERT_NE(pid, -1); + + if (pid == 0) { + /* Child: write to trigger COW */ + region[0] = 0xbb; + + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); + ASSERT_NE(pagemap_fd, -1); + child_pfn = pagemap_get_pfn(pagemap_fd, region); + close(pagemap_fd); + + /* Expect PFN to differ after write (COW happened) */ + if (child_pfn == parent_pfn) + _exit(FAIL_ON_CHECK); + _exit(0); + } + + waitpid(pid, &status, 0); + ASSERT_EQ(WEXITSTATUS(status), 0); + munmap(region, data->mapsize); +} + +TEST_HARNESS_MAIN \ No newline at end of file -- 2.34.1