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 89BA9C5B56A for ; Tue, 11 Aug 2026 15:27:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 97C6C6B0093; Tue, 11 Aug 2026 11:27:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 954516B0095; Tue, 11 Aug 2026 11:27:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86A366B0096; Tue, 11 Aug 2026 11:27:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 598B26B0093 for ; Tue, 11 Aug 2026 11:27:41 -0400 (EDT) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id CFD8F404A7 for ; Tue, 11 Aug 2026 15:27:40 +0000 (UTC) X-FDA: 85089368280.28.FEF9BCA Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf06.hostedemail.com (Postfix) with ESMTP id F32DC18000F for ; Tue, 11 Aug 2026 15:27:38 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=mC4py+uv; spf=pass (imf06.hostedemail.com: domain of brauner@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=brauner@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786462059; 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=CTiS8U5K7y3D0Dlv9kThq0rqgw/f8AQWtxw0lGe/Dc4=; b=u2blt7tn618a5QhSb8SWb++XYKAw03W74RZl/eujf3jliNK5+oageiSeOgoRTPc95q3zjt xv3kT2nPm+U6WGQjHts4qEfHp5jQLVVmwEjYNj90czWsI2B9Y5DsOt7gETWjng52dayI15 WQJcW1BsoMK9joBTl/clXXdCQOWkF94= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786462059; b=IexaCDKeVHiFqOM2zfoidkFQnB3yZs5yoqGoS4HSBlDfGp79Jjj6QOxcH1s8CXwluYwi/l /V3OWgnrYp1/ZthWz/f5Q41LiElP3vgx9aIGlQGPR2vkI8xUZF2TAEmMezx3aSCUBvdfmF 4RzgL7Nh34XErfNmza0WnAOyRMN412w= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=mC4py+uv; spf=pass (imf06.hostedemail.com: domain of brauner@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=brauner@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 41CFC43C6C; Tue, 11 Aug 2026 15:27:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 065F41F000E9; Tue, 11 Aug 2026 15:27:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786462058; bh=CTiS8U5K7y3D0Dlv9kThq0rqgw/f8AQWtxw0lGe/Dc4=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=mC4py+uvPpGye50ncXW6tN5UwwBurfR2YI6g2akn5SfoyucoN96Iuhu+NxGTOrH3o MkqTLLRiH2AM9KlPjaR2x0/fyxoEibIafXOO4O/yk+7kseDcfoaIkc5ywjS76KIh58 uTZGsjBx58J2PC81zMZyAa3QR4lsnnkWNkaeafOqjDnExeGsfDgFeg0O0m2o91+zjy TB1TdF8O5kIbuCnLqub754cG/W44hcDiRBfFXlySYmvNGiETfFDzTm3//KQOSCridE jgNVU4iczl3HxAAwk/QzeZhQD+wpVjBU0+izdycJrar7GDIr9osZh/vZGtrcxKAzJR Hkb2FHgVGGr3A== From: Christian Brauner Date: Tue, 11 Aug 2026 17:27:22 +0200 Subject: [PATCH 01/11] selftests/coredump: discard the right amount after the coredump request MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260811-work-coredump-sparse-v1-1-cd3e8b1e356d@kernel.org> References: <20260811-work-coredump-sparse-v1-0-cd3e8b1e356d@kernel.org> In-Reply-To: <20260811-work-coredump-sparse-v1-0-cd3e8b1e356d@kernel.org> To: Jacob Lalonde , Josef Bacik Cc: Alexander Viro , Jan Kara , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Omar Sandoval , Jacob Lalonde , Shuah Khan , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, "Christian Brauner (Amutable)" X-Mailer: b4 0.17-dev-362b8 X-Developer-Signature: v=1; a=openpgp-sha256; l=2068; i=brauner@kernel.org; h=from:subject:message-id; bh=9qfTBP7vyCivJLvwjV8igaT+fa50Nmgpl18ZhB0KXys=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWRV2ydMf7Yj5mq10YbIOXkbJ95a9/zScZZbVZry5XOvO yzzO73VuqOUhUGMi0FWTJHFod0kXG45T8Vmo0wNmDmsTCBDGLg4BWAiArMYGW7aJ8lq/vFdKsUS 29T9edfMloBLLCp5ugHMK56ferXk0nFGhubEiY8Kd3sz7VsW2vO1z4dNb8lS6azWlYGrFy32vBp iygsA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: n1ygwa8ih8n78smt3eg9jenrb57p5xt1 X-Rspamd-Queue-Id: F32DC18000F X-HE-Tag: 1786462058-103469 X-HE-Meta: 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 7qB3sQiY hdwoHhAHcrjR8vUQkfURprgOQjDg737Bhr26+GD0ZpP3ZWRngGMMvuBDWOkEz/GktW0eWaPqISWsY8l+IYyEkNmplsV/ALaasLsZk4E1Ll44OMLzTjbBjb15yPCPgpmN27lxMLQM8oEwKLC4+LTElDXgtNcrqXpS66bEqjG/Q0tFNwqsX1mOBbbqNF0ngRdihETnIDZyHM1po3zHF3ljcPSqmo4zBjyj4235ItEnOODQVNC75XD/6tYIvQw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: read_coredump_req() gets the leftover wrong twice. It takes the absolute difference of the two sizes, so a test binary that knows a larger struct coredump_req than the kernel sends tries to discard bytes that were never sent. And it hands recv() sizeof(buffer) instead of the number of bytes it wants. So MSG_WAITALL waits for a whole page. Either one blocks until the kernel closes the socket. Which it won't because it is waiting for the coredump ack... Its benign today because struct coredump_req hasn't grown. But let's fix it for the future. Compute the leftover as what the kernel sent beyond what was consumed. Fixes: 59cd658eaf40 ("selftests/coredump: add coredump server selftests") Signed-off-by: Christian Brauner (Amutable) --- tools/testing/selftests/coredump/coredump_test_helpers.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/coredump/coredump_test_helpers.c b/tools/testing/selftests/coredump/coredump_test_helpers.c index 2a20faf9cb0a..524fa5370593 100644 --- a/tools/testing/selftests/coredump/coredump_test_helpers.c +++ b/tools/testing/selftests/coredump/coredump_test_helpers.c @@ -235,10 +235,10 @@ bool read_coredump_req(int fd, struct coredump_req *req) fprintf(stderr, "Read coredump request with size %u and mask 0x%llx\n", req->size, (unsigned long long)req->mask); - if (user_size > kernel_size) - remaining_size = user_size - kernel_size; - else + if (kernel_size > user_size) remaining_size = kernel_size - user_size; + else + remaining_size = 0; if (PAGE_SIZE <= remaining_size) return false; @@ -250,7 +250,7 @@ bool read_coredump_req(int fd, struct coredump_req *req) if (remaining_size) { char buffer[PAGE_SIZE]; - ret = recv(fd, buffer, sizeof(buffer), MSG_WAITALL); + ret = recv(fd, buffer, remaining_size, MSG_WAITALL); if (ret != remaining_size) return false; fprintf(stderr, "Discarded %zu bytes of data after coredump request\n", remaining_size); -- 2.53.0