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 ED5DB3A9856; Wed, 9 Sep 2026 09:44:22 +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=1788947063; cv=none; b=aavwAdEOhCpKtUonjds9lckIaphMbHYOgUxzMjBf5mgYtKN+kU7MSZZVcn2Cf+1n1gr3FIj0R9WA/AES4ERMWVAxClTqOg1PmF6jjf/DKYSmfeaNmp0jG5aYnW/Ew3js5iSsEMH2bjJL4c2yrC06hLBmQmMlqRB89aC2Sz6nyL4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788947063; c=relaxed/simple; bh=CRNCNFOv1d/GN5B5RDOOI3W6Az4pcT/yOZ7OHd2PmTU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=BBVxST5h7z4SaXihnNlvtIQChSlsEd7U6t+61qnqCZeDAYSj4nAMutaFnA4AiOaE7t244srODWKZAguKN714l++30jT0nvFrTUrYjH83m5W3amQyNzksV5zGr/WXaL3VOm5rmxrQkauQMqSiguFJrvfXnHJMS05tUhSVBdW3jTw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ca+kykha; 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="Ca+kykha" Received: by smtp.kernel.org (Postfix) with ESMTPS id A6EB0C4AF0B; Wed, 9 Sep 2026 09:44:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1788947062; bh=CRNCNFOv1d/GN5B5RDOOI3W6Az4pcT/yOZ7OHd2PmTU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=Ca+kykhajnNckAaTgWwCtYDMwntf2X0wkKrXlvNUTTINw9pfmajZwXe2mCtVHDXkS eSzJjxzbPFw+aTWc9xCtU02u6fR0Fduew3A08cvSMVtz5i9fAxyb8eoiApeB+XL1dl uvP2eAAOTxcPT2MLZXToPLVcJDF+jwUjhY0Vtuqtv7prm0zkdH87TjRBrtX19ZT/2e fGyIhNRN4Bfb55rxaR5Sa8pvR2jYydZmc5J4NRllPJvBCJFzVTwUvmmRffLXGe4BfQ f3BnW+tiHI/RNfGA5ewq3n9IwTS5keBbKWxfKx75PoNf+xLoyVyBRkbRHBM/7fVO5g GG9JeGilqKlgA== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 885CCC79F8C; Wed, 9 Sep 2026 09:44:22 +0000 (UTC) From: linuszeng via B4 Relay Date: Wed, 09 Sep 2026 17:44:20 +0800 Subject: [PATCH v2 2/3] mm: page_counter: track protection state in page_counter_protection Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260909-descriptive-name-v2-2-d7dd7c099049@tencent.com> References: <20260909-descriptive-name-v2-0-d7dd7c099049@tencent.com> In-Reply-To: <20260909-descriptive-name-v2-0-d7dd7c099049@tencent.com> To: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Maarten Lankhorst , Maxime Ripard , Natalie Vock , Tejun Heo , =?utf-8?q?Michal_Koutn=C3=BD?= , Oscar Salvador , Jingxiang Zeng Cc: Michal Hocko , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linuszeng X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1788947061; l=9367; i=linuszeng@tencent.com; s=20260909; h=from:subject:message-id; bh=XnbhI6+XRiaUlggWoaB82VSvLpQ+T9RolGkd/4opeEI=; b=5VgMCSoPCaXiCqb5wg+bntHG8d6Ak9j8BQa82fZVBGqZccF2FPppQ4a8KIUtrqj7tSklZX58w J1XUmGOlDWkCMxeVIF2N7KV/UqP5LXntzd+BqFlzw8g7w4RgPHAeSVX X-Developer-Key: i=linuszeng@tencent.com; a=ed25519; pk=6K54xRzYIRWqatrAPy86M4E0MsI92BVJBhXwz5NdC74= X-Endpoint-Received: by B4 Relay for linuszeng@tencent.com/20260909 with auth_id=1017 X-Original-From: linuszeng Reply-To: linuszeng@tencent.com From: linuszeng Move the read/write side of hierarchical protection from struct page_counter to struct page_counter_protection: propagate_protected_usage() updates the protection context of the parent, page_counter_set_min()/low() and page_counter_calculate_protection() operate on it, and memcg and dmem accessors (including dmem_cgroup_below_min()/below_low()) read min/low/emin/elow and children_*_usage from it. struct page_counter keeps its now-unused protection fields for now; they are removed in a follow-up commit. No functional change. --- include/linux/memcontrol.h | 8 +++---- kernel/cgroup/dmem.c | 12 +++++----- mm/memcontrol.c | 8 +++---- mm/page_counter.c | 59 +++++++++++++++++++++++++++++----------------- 4 files changed, 52 insertions(+), 35 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index ed863f4ed233..44065001a66a 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -591,8 +591,8 @@ static inline void mem_cgroup_protection(struct mem_cgroup *root, if (root == memcg) return; - *min = READ_ONCE(memcg->memory.emin); - *low = READ_ONCE(memcg->memory.elow); + *min = READ_ONCE(memcg->memory_prot.emin); + *low = READ_ONCE(memcg->memory_prot.elow); } void mem_cgroup_calculate_protection(struct mem_cgroup *root, @@ -616,7 +616,7 @@ static inline bool mem_cgroup_below_low(struct mem_cgroup *target, if (mem_cgroup_unprotected(target, memcg)) return false; - return READ_ONCE(memcg->memory.elow) >= + return READ_ONCE(memcg->memory_prot.elow) >= page_counter_read(&memcg->memory); } @@ -626,7 +626,7 @@ static inline bool mem_cgroup_below_min(struct mem_cgroup *target, if (mem_cgroup_unprotected(target, memcg)) return false; - return READ_ONCE(memcg->memory.emin) >= + return READ_ONCE(memcg->memory_prot.emin) >= page_counter_read(&memcg->memory); } diff --git a/kernel/cgroup/dmem.c b/kernel/cgroup/dmem.c index a4bac0d5ac3b..4027d3d309c8 100644 --- a/kernel/cgroup/dmem.c +++ b/kernel/cgroup/dmem.c @@ -212,12 +212,12 @@ set_resource_max(struct dmem_cgroup_pool_state *pool, u64 val, bool nonblock) static u64 get_resource_low(struct dmem_cgroup_pool_state *pool) { - return pool ? READ_ONCE(pool->cnt.low) : 0; + return pool ? READ_ONCE(pool->cnt.prot->low) : 0; } static u64 get_resource_min(struct dmem_cgroup_pool_state *pool) { - return pool ? READ_ONCE(pool->cnt.min) : 0; + return pool ? READ_ONCE(pool->cnt.prot->min) : 0; } static u64 get_resource_max(struct dmem_cgroup_pool_state *pool) @@ -388,13 +388,13 @@ bool dmem_cgroup_state_evict_valuable(struct dmem_cgroup_pool_state *limit_pool, dmem_cgroup_calculate_protection(limit_pool, test_pool); used = page_counter_read(ctest); - min = READ_ONCE(ctest->emin); + min = READ_ONCE(ctest->prot->emin); if (used <= min) return false; if (!ignore_low) { - low = READ_ONCE(ctest->elow); + low = READ_ONCE(ctest->prot->elow); if (used > low) return true; @@ -787,7 +787,7 @@ bool dmem_cgroup_below_min(struct dmem_cgroup_pool_state *root, * here. */ dmem_cgroup_calculate_protection(root, test); - return page_counter_read(&test->cnt) <= READ_ONCE(test->cnt.emin); + return page_counter_read(&test->cnt) <= READ_ONCE(test->cnt.prot->emin); } EXPORT_SYMBOL_GPL(dmem_cgroup_below_min); @@ -818,7 +818,7 @@ bool dmem_cgroup_below_low(struct dmem_cgroup_pool_state *root, * here. */ dmem_cgroup_calculate_protection(root, test); - return page_counter_read(&test->cnt) <= READ_ONCE(test->cnt.elow); + return page_counter_read(&test->cnt) <= READ_ONCE(test->cnt.prot->elow); } EXPORT_SYMBOL_GPL(dmem_cgroup_below_low); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ffa1ced3baae..b4c01a0dfd4f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4823,7 +4823,7 @@ static ssize_t memory_peak_write(struct kernfs_open_file *of, char *buf, static int memory_min_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, - READ_ONCE(mem_cgroup_from_seq(m)->memory.min)); + READ_ONCE(mem_cgroup_from_seq(m)->memory_prot.min)); } static ssize_t memory_min_write(struct kernfs_open_file *of, @@ -4846,7 +4846,7 @@ static ssize_t memory_min_write(struct kernfs_open_file *of, static int memory_low_show(struct seq_file *m, void *v) { return seq_puts_memcg_tunable(m, - READ_ONCE(mem_cgroup_from_seq(m)->memory.low)); + READ_ONCE(mem_cgroup_from_seq(m)->memory_prot.low)); } static ssize_t memory_low_write(struct kernfs_open_file *of, @@ -6271,6 +6271,6 @@ void mem_cgroup_show_protected_memory(struct mem_cgroup *memcg) memcg = root_mem_cgroup; pr_warn("Memory cgroup min protection %lukB -- low protection %lukB", - K(atomic_long_read(&memcg->memory.children_min_usage)), - K(atomic_long_read(&memcg->memory.children_low_usage))); + K(atomic_long_read(&memcg->memory_prot.children_min_usage)), + K(atomic_long_read(&memcg->memory_prot.children_low_usage))); } diff --git a/mm/page_counter.c b/mm/page_counter.c index 38cb99f5f50e..401201c8e390 100644 --- a/mm/page_counter.c +++ b/mm/page_counter.c @@ -21,28 +21,29 @@ static bool track_protection(struct page_counter *c) static void propagate_protected_usage(struct page_counter *c, unsigned long usage) { + struct page_counter_protection *prot = c->prot; unsigned long protected, old_protected; long delta; - if (!c->parent) + if (!prot || !prot->parent) return; - protected = min(usage, READ_ONCE(c->min)); - old_protected = atomic_long_read(&c->min_usage); + protected = min(usage, READ_ONCE(prot->min)); + old_protected = atomic_long_read(&prot->min_usage); if (protected != old_protected) { - old_protected = atomic_long_xchg(&c->min_usage, protected); + old_protected = atomic_long_xchg(&prot->min_usage, protected); delta = protected - old_protected; if (delta) - atomic_long_add(delta, &c->parent->children_min_usage); + atomic_long_add(delta, &prot->parent->children_min_usage); } - protected = min(usage, READ_ONCE(c->low)); - old_protected = atomic_long_read(&c->low_usage); + protected = min(usage, READ_ONCE(prot->low)); + old_protected = atomic_long_read(&prot->low_usage); if (protected != old_protected) { - old_protected = atomic_long_xchg(&c->low_usage, protected); + old_protected = atomic_long_xchg(&prot->low_usage, protected); delta = protected - old_protected; if (delta) - atomic_long_add(delta, &c->parent->children_low_usage); + atomic_long_add(delta, &prot->parent->children_low_usage); } } @@ -257,7 +258,10 @@ void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages) { struct page_counter *c; - WRITE_ONCE(counter->min, nr_pages); + if (!counter->prot) + return; + + WRITE_ONCE(counter->prot->min, nr_pages); for (c = counter; c; c = c->parent) propagate_protected_usage(c, atomic_long_read(&c->usage)); @@ -274,7 +278,10 @@ void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages) { struct page_counter *c; - WRITE_ONCE(counter->low, nr_pages); + if (!counter->prot) + return; + + WRITE_ONCE(counter->prot->low, nr_pages); for (c = counter; c; c = c->parent) propagate_protected_usage(c, atomic_long_read(&c->usage)); @@ -445,9 +452,18 @@ void page_counter_calculate_protection(struct page_counter *root, struct page_counter *counter, bool recursive_protection) { + struct page_counter_protection *prot = counter->prot; + struct page_counter_protection *parent_prot; unsigned long usage, parent_usage; struct page_counter *parent = counter->parent; + /* + * Only counters with protection support (memory, dmem pools) are + * ever passed here, but guard anyway. + */ + if (!prot) + return; + /* * Effective values of the reclaim targets are ignored so they * can be stale. Have a look at mem_cgroup_protection for more @@ -463,23 +479,24 @@ void page_counter_calculate_protection(struct page_counter *root, return; if (parent == root) { - counter->emin = READ_ONCE(counter->min); - counter->elow = READ_ONCE(counter->low); + prot->emin = READ_ONCE(prot->min); + prot->elow = READ_ONCE(prot->low); return; } + parent_prot = parent->prot; parent_usage = page_counter_read(parent); - WRITE_ONCE(counter->emin, effective_protection(usage, parent_usage, - READ_ONCE(counter->min), - READ_ONCE(parent->emin), - atomic_long_read(&parent->children_min_usage), + WRITE_ONCE(prot->emin, effective_protection(usage, parent_usage, + READ_ONCE(prot->min), + READ_ONCE(parent_prot->emin), + atomic_long_read(&parent_prot->children_min_usage), recursive_protection)); - WRITE_ONCE(counter->elow, effective_protection(usage, parent_usage, - READ_ONCE(counter->low), - READ_ONCE(parent->elow), - atomic_long_read(&parent->children_low_usage), + WRITE_ONCE(prot->elow, effective_protection(usage, parent_usage, + READ_ONCE(prot->low), + READ_ONCE(parent_prot->elow), + atomic_long_read(&parent_prot->children_low_usage), recursive_protection)); } #endif /* CONFIG_MEMCG || CONFIG_CGROUP_DMEM */ -- 2.43.7