From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1181336F41F for ; Sun, 29 Mar 2026 16:12:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774800729; cv=none; b=ZnAeQVMFdHDrMcGs/Ji/Fz/IiIyPebM1VoYe0qXWiZ802DG9ff6aeIEkiCPFdYyLqWNrUs+DMyaQdT2uiF9Sy0vGGUcDofnrTPLOrSRHVUM7ZcsXFoSzIQk6qx8T1j0YR1cxj0J3jt3wyFrXPMDAt3x2aQe7c7YpFGto7PlfKcQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774800729; c=relaxed/simple; bh=xwKFAOav4tp7RJR6OFW4vEA/lv/KH+0e6Oj7r3dOTWE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZNXV0i0oyhnbqVahMLSVf8E1MM+sORsuVofONu2YauUJRUV+SPLuwcq1hq+/MQEPouqrY85avKeIuPsIZcjsOjS8INZWLw075sOsGMJgNakiTq9vIvVOTZBc7Qh80w3eusw4ZSCjpCffGyZns5sUJROIjnpQuMFYGLlaDE61gOA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lgH5LvjA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lgH5LvjA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87848C116C6; Sun, 29 Mar 2026 16:12:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774800728; bh=xwKFAOav4tp7RJR6OFW4vEA/lv/KH+0e6Oj7r3dOTWE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lgH5LvjAXlLGVukWXo45LauUYzLyd3t3IOEUpw01LAkDWQu74nrLNufyex/155PUR OwAeT6pBE3wOE4ZOOtmQibnGHgL4uUN9jXJWLIyXP5Bg61BFdB5ctNTDQRyr9lLPx5 smDOoUSZyBBnWRX5Ah5xwCikoDk3p1P3MITfk/eDe3oSqmpYiAed1ouEGVgHw3+u6g fL67sAzaZOuakCFWgaoHkg0D1VJTSp0MC6x87XBQUdWyO3CeuwpnGTi51KQ9nrpXyA 5iEvMmMuO6pyci0VB8tG8rPhPoQYz0FKKAnQ72xTRXQo0xnvez4pv3mRae/ewr0ey5 hRu5ySz4ZVLGw== From: SeongJae Park To: stable@vger.kernel.org Cc: SeongJae Park , Andrew Morton Subject: [PATCH 6.18.y] mm/damon/stat: monitor all System RAM resources Date: Sun, 29 Mar 2026 09:12:04 -0700 Message-ID: <20260329161204.53291-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <2026032915-elastic-replay-88fe@gregkh> References: <2026032915-elastic-replay-88fe@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit DAMON_STAT usage document (Documentation/admin-guide/mm/damon/stat.rst) says it monitors the system's entire physical memory. But, it is monitoring only the biggest System RAM resource of the system. When there are multiple System RAM resources, this results in monitoring only an unexpectedly small fraction of the physical memory. For example, suppose the system has a 500 GiB System RAM, 10 MiB non-System RAM, and 500 GiB System RAM resources in order on the physical address space. DAMON_STAT will monitor only the first 500 GiB System RAM. This situation is particularly common on NUMA systems. Select a physical address range that covers all System RAM areas of the system, to fix this issue and make it work as documented. [sj@kernel.org: return error if monitoring target region is invalid] Link: https://lkml.kernel.org/r/20260317053631.87907-1-sj@kernel.org Link: https://lkml.kernel.org/r/20260316235118.873-1-sj@kernel.org Fixes: 369c415e6073 ("mm/damon: introduce DAMON_STAT module") Signed-off-by: SeongJae Park Cc: [6.17+] Signed-off-by: Andrew Morton (cherry picked from commit 84481e705ab07ed46e56587fe846af194acacafe) Signed-off-by: SeongJae Park --- mm/damon/stat.c | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) diff --git a/mm/damon/stat.c b/mm/damon/stat.c index bf8626859902..a8d6a3049830 100644 --- a/mm/damon/stat.c +++ b/mm/damon/stat.c @@ -145,12 +145,44 @@ static int damon_stat_damon_call_fn(void *data) return 0; } +struct damon_stat_system_ram_range_walk_arg { + bool walked; + struct resource res; +}; + +static int damon_stat_system_ram_walk_fn(struct resource *res, void *arg) +{ + struct damon_stat_system_ram_range_walk_arg *a = arg; + + if (!a->walked) { + a->walked = true; + a->res.start = res->start; + } + a->res.end = res->end; + return 0; +} + +static int damon_stat_set_monitoring_region(struct damon_target *t, + unsigned long addr_unit) +{ + struct damon_addr_range addr_range; + struct damon_stat_system_ram_range_walk_arg arg = {}; + + walk_system_ram_res(0, ULONG_MAX, &arg, damon_stat_system_ram_walk_fn); + if (!arg.walked) + return -EINVAL; + addr_range.start = arg.res.start; + addr_range.end = arg.res.end + 1; + if (addr_range.end <= addr_range.start) + return -EINVAL; + return damon_set_regions(t, &addr_range, 1, DAMON_MIN_REGION); +} + static struct damon_ctx *damon_stat_build_ctx(void) { struct damon_ctx *ctx; struct damon_attrs attrs; struct damon_target *target; - unsigned long start = 0, end = 0; ctx = damon_new_ctx(); if (!ctx) @@ -188,7 +220,7 @@ static struct damon_ctx *damon_stat_build_ctx(void) if (!target) goto free_out; damon_add_target(ctx, target); - if (damon_set_region_biggest_system_ram_default(target, &start, &end)) + if (damon_stat_set_monitoring_region(target, ctx->addr_unit)) goto free_out; return ctx; free_out: -- 2.47.3