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cgroup/cpuset: update some comments about the page allocator

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These comments describing the page allocator are out of date: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It may be out of date for other reasons too but this patch is just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- Completely drop out-of-date details of that function's internal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 <jackmanb@google.com>
Suggested-by: Zi Yan <ziy@nvidia.com>
Link: https://lore.kernel.org/all/DJP11T5V7BDW.2FZZZ8R6LOY4I@nvidia.com/
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Brendan Jackman 2026-07-15 11:03:19 +00:00 committed by Andrew Morton
parent 21be908d39
commit 0cce423a12
1 changed files with 5 additions and 8 deletions
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13
kernel/cgroup/cpuset.c
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@ -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().
*/