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Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu

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Pull percpu updates from Dennis Zhou:

 - percpu chunk depopulation - depopulate backing pages for chunks with
   empty pages when we exceed a global threshold without those pages.
   This lets us reclaim a portion of memory that would previously be
   lost until the full chunk would be freed (possibly never).

 - memcg accounting cleanup - previously separate chunks were managed
   for normal allocations and __GFP_ACCOUNT allocations. These are now
   consolidated which cleans up the code quite a bit.

 - a few misc clean ups for clang warnings

* 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
  percpu: optimize locking in pcpu_balance_workfn()
  percpu: initialize best_upa variable
  percpu: rework memcg accounting
  mm, memcg: introduce mem_cgroup_kmem_disabled()
  mm, memcg: mark cgroup_memory_nosocket, nokmem and noswap as __ro_after_init
  percpu: make symbol 'pcpu_free_slot' static
  percpu: implement partial chunk depopulation
  percpu: use pcpu_free_slot instead of pcpu_nr_slots - 1
  percpu: factor out pcpu_check_block_hint()
  percpu: split __pcpu_balance_workfn()
  percpu: fix a comment about the chunks ordering
This commit is contained in:
Linus Torvalds
2021-07-01 17:17:24 -07:00
parent 19b4385922 e4d777003a
commit e267992f9e
7 changed files with 343 additions and 186 deletions
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35
mm/percpu-vm.c
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@@ -329,13 +329,12 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
pcpu_free_pages(chunk, pages, page_start, page_end);
}
static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
gfp_t gfp)
static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
{
struct pcpu_chunk *chunk;
struct vm_struct **vms;
chunk = pcpu_alloc_chunk(type, gfp);
chunk = pcpu_alloc_chunk(gfp);
if (!chunk)
return NULL;
@@ -378,3 +377,33 @@ static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
/* no extra restriction */
return 0;
}
/**
* pcpu_should_reclaim_chunk - determine if a chunk should go into reclaim
* @chunk: chunk of interest
*
* This is the entry point for percpu reclaim. If a chunk qualifies, it is then
* isolated and managed in separate lists at the back of pcpu_slot: sidelined
* and to_depopulate respectively. The to_depopulate list holds chunks slated
* for depopulation. They no longer contribute to pcpu_nr_empty_pop_pages once
* they are on this list. Once depopulated, they are moved onto the sidelined
* list which enables them to be pulled back in for allocation if no other chunk
* can suffice the allocation.
*/
static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
{
/* do not reclaim either the first chunk or reserved chunk */
if (chunk == pcpu_first_chunk || chunk == pcpu_reserved_chunk)
return false;
/*
* If it is isolated, it may be on the sidelined list so move it back to
* the to_depopulate list. If we hit at least 1/4 pages empty pages AND
* there is no system-wide shortage of empty pages aside from this
* chunk, move it to the to_depopulate list.
*/
return ((chunk->isolated && chunk->nr_empty_pop_pages) ||
(pcpu_nr_empty_pop_pages >
(PCPU_EMPTY_POP_PAGES_HIGH + chunk->nr_empty_pop_pages) &&
chunk->nr_empty_pop_pages >= chunk->nr_pages / 4));
}