From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B09ED362130 for ; Tue, 4 Aug 2026 00:48:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785804537; cv=none; b=sfEHRoVsyW4JcJeyYJf+w6KZS0Uzrb+lMpT5hennl7AzWuxd3axJp1+CjiT5TduxvZpugVIV+EbLOHwC9JZksA2MNXJAsVDAOGq3PfYvz28xeRtjzSPqYfbBVJ3dLkR3rnJrjpSFvue2YMaSV+tjgGrkk+bdriG1Mpu++j04f0s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785804537; c=relaxed/simple; bh=i1PqfE7fiCQpTCfsVVj+Urj0yUCYWUWxyJ511DEdQCE=; h=Date:To:From:Subject:Message-Id; b=u7oLn8JEmK+mHqRiCpmKFO16Zi2LXYnWsv1YW9eqgiXDEMgCuuodFhbJmZqlnCvU5Ni6WvQiMBQtKmL8i31Yt0vdalgCnBRcotVDr2BDfSCDThcl+OFTB4WqgDKQrRgGRwfRNQMTDr7YTu1Qww6cmC1AGYS5pPDpf8xOnfuQ7JY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=UZsP/HTS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="UZsP/HTS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3DD531F000E9; Tue, 4 Aug 2026 00:48:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1785804535; bh=wp3upry5NO4SMvLCTPE4G12yL2B9GNndUjRY2Nxie14=; h=Date:To:From:Subject; b=UZsP/HTSsf34E6lOhw7ijeSGiDNnxvn2UyfqYn/ddeMWDTZ1YIvFW+VULrnRofUof t4ZGNg2QA/RSAB21CdGwbuRZHa0F8Jf364Pvr1JoMEE4qLpesBYccDjerwerkCsRlJ QaAlmDcZgnQhh1LwHve8gOVxajtEDMG8yoD+bU3s= Date: Mon, 03 Aug 2026 17:48:54 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,vbabka@kernel.org,surenb@google.com,mhocko@suse.com,jackmanb@google.com,hannes@cmpxchg.org,shijianlin11@foxmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-page_alloc-only-update-lowmem_reserve_ratio-on-sysctl-write.patch added to mm-unstable branch Message-Id: <20260804004855.3DD531F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/page_alloc: only update lowmem_reserve_ratio on sysctl write has been added to the -mm mm-unstable branch. Its filename is mm-page_alloc-only-update-lowmem_reserve_ratio-on-sysctl-write.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-only-update-lowmem_reserve_ratio-on-sysctl-write.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Jianlin Shi Subject: mm/page_alloc: only update lowmem_reserve_ratio on sysctl write Date: Sun, 2 Aug 2026 22:57:07 +0800 lowmem_reserve_ratio_sysctl_handler() ignores the return value of proc_dointvec_minmax() and always calls setup_per_zone_lowmem_reserve(), even for read operations. Fix three issues: 1. Propagate errors from proc_dointvec_minmax() instead of always returning success. For example, writing non-integer garbage to the sysctl now returns an error instead of silently succeeding with unchanged values. 2. Only call setup_per_zone_lowmem_reserve() when the sysctl is actually written, matching the write-only refresh pattern of min_free_kbytes and watermark_scale_factor handlers. 3. On write, parse into a temporary ratio[] array and only copy into sysctl_lowmem_reserve_ratio[] and refresh derived state after the full vector is validated. This avoids leaving the ratio array partially updated while skipping setup when proc_dointvec_minmax() returns an error on a later element (suggested by Andrew Morton). Drop the manual "< 1 -> 0" sanitization loop and set .extra1 = SYSCTL_ZERO on the ctl_table entry so proc_dointvec_minmax() enforces the minimum on write; negative values now return -EINVAL instead of being silently coerced to 0 (suggested by Vlastimil Babka). Link: https://lore.kernel.org/tencent_B9556590D4B65ACF74C06897689A6E39F206@qq.com Link: https://lore.kernel.org/linux-mm/tencent_FFD4F4D728AAE8A8AE0AF277A59854A29A06@qq.com/ Signed-off-by: Jianlin Shi Cc: Brendan Jackman Cc: Johannes Weiner Cc: Michal Hocko Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/page_alloc.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-only-update-lowmem_reserve_ratio-on-sysctl-write +++ a/mm/page_alloc.c @@ -6915,8 +6915,8 @@ static int sysctl_min_slab_ratio_sysctl_ /* * lowmem_reserve_ratio_sysctl_handler - just a wrapper around - * proc_dointvec() so that we can call setup_per_zone_lowmem_reserve() - * whenever sysctl_lowmem_reserve_ratio changes. + * proc_dointvec_minmax() so that we can call + * setup_per_zone_lowmem_reserve() when the sysctl is written. * * The reserve ratio obviously has absolutely no relation with the * minimum watermarks. The lowmem reserve ratio can only make sense @@ -6925,16 +6925,23 @@ static int sysctl_min_slab_ratio_sysctl_ static int lowmem_reserve_ratio_sysctl_handler(const struct ctl_table *table, int write, void *buffer, size_t *length, loff_t *ppos) { - int i; + struct ctl_table tmp = *table; + int ratio[MAX_NR_ZONES]; + int rc; - proc_dointvec_minmax(table, write, buffer, length, ppos); + if (!write) + return proc_dointvec_minmax(table, write, buffer, length, ppos); - for (i = 0; i < MAX_NR_ZONES; i++) { - if (sysctl_lowmem_reserve_ratio[i] < 1) - sysctl_lowmem_reserve_ratio[i] = 0; - } + memcpy(ratio, sysctl_lowmem_reserve_ratio, sizeof(ratio)); + tmp.data = ratio; + rc = proc_dointvec_minmax(&tmp, write, buffer, length, ppos); + if (rc) + return rc; + + memcpy(sysctl_lowmem_reserve_ratio, ratio, sizeof(ratio)); setup_per_zone_lowmem_reserve(); + return 0; } @@ -7033,6 +7040,7 @@ static const struct ctl_table page_alloc .maxlen = sizeof(sysctl_lowmem_reserve_ratio), .mode = 0644, .proc_handler = lowmem_reserve_ratio_sysctl_handler, + .extra1 = SYSCTL_ZERO, }, #ifdef CONFIG_NUMA { _ Patches currently in -mm which might be from shijianlin11@foxmail.com are mm-page_alloc-only-update-lowmem_reserve_ratio-on-sysctl-write.patch ipc-only-destroy-orphaned-shm-segments-on-sysctl-write.patch