From 0cce423a1253c55a8b86fa9aaf82715d0a813dad Mon Sep 17 00:00:00 2001 From: Brendan Jackman Date: Wed, 15 Jul 2026 11:03:19 +0000 Subject: [PATCH] cgroup/cpuset: update some comments about the page allocator MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit These comments describing the page allocator are out of date: - __alloc_pages() is no longer a public API and has no business being described outside of mm/. - The `wait` variable is gone. It may be out of date for other reasons too but this patch is just fixing the issues that stood out. To fix it: - Instead of referring to a specific function, instead to "the page allocator" - Completely drop out-of-date details of that function's internal behaviour, since they were irrelevant anyway. Link: https://lore.kernel.org/20260715-spin-trylock-followup-v3-2-fc4d246f705d@google.com Signed-off-by: Brendan Jackman Suggested-by: Zi Yan Link: https://lore.kernel.org/all/DJP11T5V7BDW.2FZZZ8R6LOY4I@nvidia.com/ Reviewed-by: Zi Yan Reviewed-by: Vlastimil Babka (SUSE) Acked-by: Tejun Heo Cc: David Hildenbrand Cc: Johannes Weiner Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Michal Koutný Cc: Mike Rapoport Cc: Sebastian Andrzej Siewior Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Waiman Long Cc: Brendan Jackman Signed-off-by: Andrew Morton --- kernel/cgroup/cpuset.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 92484b293689..ee4025b9707a 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -4198,7 +4198,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) * nearest enclosing hardwalled ancestor cpuset. * * Scanning up parent cpusets requires callback_lock. The - * __alloc_pages() routine only calls here with __GFP_HARDWALL bit + * page allocator only calls here with __GFP_HARDWALL bit * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the * current tasks mems_allowed came up empty on the first pass over * the zonelist. So only GFP_KERNEL allocations, if all nodes in the @@ -4211,11 +4211,8 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) * come before the __GFP_HARDWALL check, otherwise a dying task * would be blocked on the fast path. * - * The second pass through get_page_from_freelist() doesn't even call - * here for GFP_ATOMIC calls. For those calls, the __alloc_pages() - * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set - * in alloc_flags. That logic and the checks below have the combined - * affect that: + * The second pass through get_page_from_freelist() doesn't even call here for + * GFP_ATOMIC calls. That, and the checks below have the combined affect that: * in_interrupt - any node ok (current task context irrelevant) * GFP_ATOMIC - any node ok * tsk_is_oom_victim - any node ok @@ -4332,8 +4329,8 @@ void cpuset_nodes_allowed(struct cgroup *cgroup, nodemask_t *mask) * should not be possible for the following code to return an * offline node. But if it did, that would be ok, as this routine * is not returning the node where the allocation must be, only - * the node where the search should start. The zonelist passed to - * __alloc_pages() will include all nodes. If the slab allocator + * the node where the search should start. The zonelist used by + * the allocator will include all nodes. If the slab allocator * is passed an offline node, it will fall back to the local node. * See kmem_cache_alloc_node(). */