From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 65D85606A32D for ; Sat, 7 Nov 2026 22:22:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=FqsDAE7f Received: by kanga.kvack.org (Postfix) id 1B1086B05B5; Sat, 7 Nov 2026 17:22:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0C50E6B05B7; Sat, 7 Nov 2026 17:22:14 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E5D9E6B05B5; Sat, 7 Nov 2026 17:22:14 -0500 (EST) 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 B4C636B05B5 for ; Sat, 7 Nov 2026 17:22:14 -0500 (EST) Received: from smtpin24.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 231AA80250 for ; Sat, 7 Nov 2026 22:22:14 +0000 (UTC) X-FDA: 85409747388.24.BA22582 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf25.hostedemail.com (Postfix) with ESMTP id 7202DA0007 for ; Sat, 7 Nov 2026 22:22:12 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FqsDAE7f; spf=pass (imf25.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@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=1794090132; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=e8b2BxiNM2zDfbsfHX5lOdltBPseBRShaz9qPJkxXRw=; b=rAxEU1ofUbUrU/o8XZilnUH98MDW86chgt4AQuNH2ciH/WtUZVq3KRb+ikwJAF95ZGx3nP RnZT5+wWmerY4PWLU1oB4WvzHeHwFNQagSPvWJKgQ0vQG5XJGkwS6nfNudCxtUAIcqw69D 1eTXY0T3R1lyAcZf3ya+xBQRD58QFwU= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794090132; b=75a5wj+APBFD4QW40FcDcCatVFdaSyAbiW9QGfzbnNjQYhVU0BnsM7Cfv7BZfrcDc1PHFu y5UtR4G6Vo8SFEWNuaP8WyG2Lg2sx/rxLhvmJLAvtKuxpG9cv5kdSWN3p0ESyTUba8mjDq 1VdtV4i68J8MirMqJu8nhLO8IAFad/4= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FqsDAE7f; spf=pass (imf25.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@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 8D6EA43ED0; Sat, 7 Nov 2026 22:22:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 402281F008A3; Sat, 7 Nov 2026 22:22:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794090131; bh=e8b2BxiNM2zDfbsfHX5lOdltBPseBRShaz9qPJkxXRw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FqsDAE7f+a160tFFkgUqjUF6DTdHtN56zbOQZufBN6+E2VrZnKvqyakwl9OdCuNWf 7Kn9rtFQ3Ti9t+yZXjqVADYgS6eBXqRgznjBHQvKHWo+8KfF0SVVgx2SYhPCODCW/v VzzW7/KzL8x/XBJ/ADaQXCrF94L7vHXFNArCz1KB01j6JW4NWbUcB2sQsKKRSXDmil 8MvXTzdjgpD0LvMZq2kRz8YezFtGlUOVpZU/ISC7ZaYWTDEk5Qjri1mer7zQfxVeDH 2y8B31pkpEt6hnDgwpYWZGdTa4tggab5HxuVd85yr7BJIfOLHC0g2NQ7LFp6HSRUj3 zMyGK3GoED4dg== From: SJ Park To: Cc: SJ Park , stable@vger.kernel.org, Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 6.6.y 2/3] mm/damon/core: filter out damos address filter-split failed region Date: Sat, 7 Nov 2026 14:22:00 -0800 Message-ID: <20261107222202.331476-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261107222202.331476-1-sj@kernel.org> References: <20261107222202.331476-1-sj@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: 6h9fq3o95b3ugd8b13q8dcssx4y63bbx X-Rspamd-Queue-Id: 7202DA0007 X-Rspam-User: X-HE-Tag: 1794090132-981584 X-HE-Meta: U2FsdGVkX1+FydUKnSs8Q5ksNZHT1P+MGp0173YMLvuN4uOpwgtljMk9i+8T6gblq+xyxuaUD6rGh1CM3cEquWf4aGCkAnhAlGZ7iA0EnUf5sL0JbXr3qsJT6GQepuqDbH24NgH185DqV8xtVh8H30ivr44ZmSqzMs9egP3mNQu8uMmnFwsktLqPxNq+FXLtOuZ7t/XbT84+qgoS59hpRWQaUFZFPIVMij2tgJ9hUiWUHimJKyA999NK/tjIRJpgen9ucUijUeTsG28WfiFzx7tzmCJv5cTCLtYnK7+4jZQ/9qkQFIzQyP16V2uCnk0n5AD4SIJYbHWtooMrVHlZDLpOmkGLKDYuzybq/0TToI3yWDrQr/m3yx8Hey3a/5vjYu10jiO2LLf7cofgYJ6CKhq8pVUfrmgXKmWGRu1ve3woK5Pn1LThLWvkWeOBzs4w1FMoPwOekYjeVSjsxvOv8aLEBp94t+CczcxO42ldnKWOeXzbaNt0klkm1E/vxS7TedTr5cQ3ZLMm0UCBlG6NzYcrAyYzcabB1fnkm0VekUovb3iFeYLKXhQ4tOIbmoLD6xktbV+pWa9EPiIJoj36J75gW0HFffNBXzJ4dNx9FH+jMYHtC7rMFfm8xwCL9bfFZsdu4QsaZH9FnOFVZ+K6W5J2sSgU4T67aorFi6nCBPlYNijieblEAUQfh1QKCgpkNH0EvsxQnzikC0njwXwTutGmg9i/+hR9CYlOaJ4REVsLTSgHmy3kA24Oiq9cmYvh+Qdfgp24dr4uB2dj4XnKK7IuoMXWo12gCvK+3uy30HdP/WwrVE9f6kv2MT2SxYNcjM9Y1JagROvcNL19xZ3Z5ZP7/X4souLfHnd9/e7ZGp8rjFbVgjC6IUFigjJLGR9aGTnvwO+A1V42VRiMOQCGBy6vT9P6zCTOpVHm5eNrY4T8QPO2qZlnUZDUAy7WoxUt1WuACRJ8WekRGlALAhI fVpph32k acGe+9Rxb4GEUYeD5sbpsi9d754ABOYTXoeg77YL8FsXT60r8H9Av3qlmPlNhxAFV+GSthDsi70lYT1nDAgJuSmltRgXbyDMODNAatf1oUMeF6y/ihwZMCp5ZIo6bPOPv8sOYoWQSwrszmHpDaTOSIiiqQK7phST+N0PKBYrT0N3f5kjkXA0ewqsW6oyt1/z3V9smNejxeG47uD3lfrEZ2KotEumJCVXhz9g2x3NlawwkmqgWyG8NBkLthOVWzBPTi+o6ky3kVNvGxa5YrqESFQ+PyQzHuRp/rLm2 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 When an address type DAMOS filter is configured, DAMOS tries to split the region for the filter range, and apply DAMOS action to the filter-in region. The split operation (damon_split_region_at()) could fail from allocation failure under extreme memory pressure. In the case, DAMOS action could be applied more or less than expected, ignoring the address filter. The issue only rarely happens under extreme memory pressure. No crash or leak happens. Occasionally not applying the action to a few regions shouldn't be a real problem. But applying the action to a region that the user has excluded via address filter could be a surprise depending on the use case. It is only theoretical. No such real case is found yet. Filter out the entire region if the split is failed. Update damos_filter_match() signature to receive the error from split. Also update kunit tests for the updated signature. The issue was discovered [1] by sashiko. Link: https://lore.kernel.org/20261020004119.106690-1-sj@kernel.org Link: https://lore.kernel.org/20260801203121.117449-1-sj@kernel.org [1] Fixes: ab9bda001b68 ("mm/damon/core: introduce address range type damos filter") Signed-off-by: SJ Park Signed-off-by: Andrew Morton Cc: # 6.6.x (cherry picked from commit bbeec2d8324d7aac438bb12dd2d22b184e0a8d43) Signed-off-by: SJ Park --- mm/damon/core-test.h | 11 ++++++----- mm/damon/core.c | 13 +++++++++---- 2 files changed, 15 insertions(+), 9 deletions(-) diff --git a/mm/damon/core-test.h b/mm/damon/core-test.h index dd91b0eea61ff..1988b7dd29e96 100644 --- a/mm/damon/core-test.h +++ b/mm/damon/core-test.h @@ -461,6 +461,7 @@ static void damos_test_filter_out(struct kunit *test) struct damon_target *t; struct damon_region *r, *r2; struct damos_filter *f; + int err; f = damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true); if (!f) @@ -482,25 +483,25 @@ static void damos_test_filter_out(struct kunit *test) damon_add_region(r, t); /* region in the range */ - KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f, &err)); KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); /* region before the range */ r->ar.start = DAMON_MIN_REGION * 1; r->ar.end = DAMON_MIN_REGION * 2; - KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f, &err)); KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); /* region after the range */ r->ar.start = DAMON_MIN_REGION * 6; r->ar.end = DAMON_MIN_REGION * 8; - KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f, &err)); KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1); /* region started before the range */ r->ar.start = DAMON_MIN_REGION * 1; r->ar.end = DAMON_MIN_REGION * 4; - KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f, &err)); /* filter should have split the region */ KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 1); KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 2); @@ -515,7 +516,7 @@ static void damos_test_filter_out(struct kunit *test) /* region started in the range */ r->ar.start = DAMON_MIN_REGION * 2; r->ar.end = DAMON_MIN_REGION * 8; - KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f)); + KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f, &err)); /* filter should have split the region */ KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 2); KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 6); diff --git a/mm/damon/core.c b/mm/damon/core.c index 9d4a78deaa06a..99e934a6d1ce9 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -930,13 +930,14 @@ static void damos_update_stat(struct damos *s, } static bool __damos_filter_out(struct damon_ctx *ctx, struct damon_target *t, - struct damon_region *r, struct damos_filter *filter) + struct damon_region *r, struct damos_filter *filter, int *err) { bool matched = false; struct damon_target *ti; int target_idx = 0; unsigned long start, end; + *err = 0; switch (filter->type) { case DAMOS_FILTER_TYPE_TARGET: damon_for_each_target(ti, ctx) { @@ -962,12 +963,13 @@ static bool __damos_filter_out(struct damon_ctx *ctx, struct damon_target *t, } /* start before the range and overlap */ if (r->ar.start < start) { - damon_split_region_at(t, r, start - r->ar.start); + *err = damon_split_region_at(t, r, + start - r->ar.start); matched = false; break; } /* start inside the range */ - damon_split_region_at(t, r, end - r->ar.start); + *err = damon_split_region_at(t, r, end - r->ar.start); matched = true; break; default: @@ -981,9 +983,12 @@ static bool damos_filter_out(struct damon_ctx *ctx, struct damon_target *t, struct damon_region *r, struct damos *s) { struct damos_filter *filter; + bool matching; + int err; damos_for_each_filter(filter, s) { - if (__damos_filter_out(ctx, t, r, filter)) + matching = __damos_filter_out(ctx, t, r, filter, &err); + if (matching || err) return true; } return false; -- 2.47.3