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percpu: make pcpu_nr_empty_pop_pages per chunk type 

nr_empty_pop_pages is used to guarantee that there are some free
populated pages to satisfy atomic allocations. Accounted and
non-accounted allocations are using separate sets of chunks,
so both need to have a surplus of empty pages.

This commit makes pcpu_nr_empty_pop_pages and the corresponding logic
per chunk type.

[Dennis]
This issue came up as I was reviewing [1] and realized I missed this.
Simultaneously, it was reported btrfs was seeing failed atomic
allocations in fsstress tests [2] and [3].

[1] https://lore.kernel.org/linux-mm/20210324190626.564297-1-guro@fb.com/
[2] https://lore.kernel.org/linux-mm/20210401185158.3275.409509F4@e16-tech.com/
[3] https://lore.kernel.org/linux-mm/CAL3q7H5RNBjCi708GH7jnczAOe0BLnacT9C+OBgA-Dx9jhB6SQ@mail.gmail.com/

Fixes: 3c7be18ac9 ("mm: memcg/percpu: account percpu memory to memory cgroups")
Cc: stable@vger.kernel.org # 5.9+
Signed-off-by: Roman Gushchin <guro@fb.com>
Tested-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
This commit is contained in:
Roman Gushchin 2021-04-07 20:57:33 -07:00 committed by Dennis Zhou
parent e49d033bdd
commit 0760fa3d8f
3 changed files with 15 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
mm/percpu-internal.h
View File

@ -87,7 +87,7 @@ extern spinlock_t pcpu_lock;
extern struct list_head *pcpu_chunk_lists;
extern int pcpu_nr_slots;
extern int pcpu_nr_empty_pop_pages;
extern int pcpu_nr_empty_pop_pages[];
extern struct pcpu_chunk *pcpu_first_chunk;
extern struct pcpu_chunk *pcpu_reserved_chunk;

9
mm/percpu-stats.c
View File

@ -145,6 +145,7 @@ static int percpu_stats_show(struct seq_file *m, void *v)
int slot, max_nr_alloc;
int *buffer;
enum pcpu_chunk_type type;
int nr_empty_pop_pages;
alloc_buffer:
spin_lock_irq(&pcpu_lock);
@ -165,7 +166,11 @@ alloc_buffer:
goto alloc_buffer;
}
#define PL(X) \
nr_empty_pop_pages = 0;
for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
nr_empty_pop_pages += pcpu_nr_empty_pop_pages[type];
#define PL(X) \
seq_printf(m, " %-20s: %12lld\n", #X, (long long int)pcpu_stats_ai.X)
seq_printf(m,
@ -196,7 +201,7 @@ alloc_buffer:
PU(nr_max_chunks);
PU(min_alloc_size);
PU(max_alloc_size);
P("empty_pop_pages", pcpu_nr_empty_pop_pages);
P("empty_pop_pages", nr_empty_pop_pages);
seq_putc(m, '\n');
#undef PU

14
mm/percpu.c
View File

@ -173,10 +173,10 @@ struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
static LIST_HEAD(pcpu_map_extend_chunks);
/*
* The number of empty populated pages, protected by pcpu_lock. The
* reserved chunk doesn't contribute to the count.
* The number of empty populated pages by chunk type, protected by pcpu_lock.
* The reserved chunk doesn't contribute to the count.
*/
int pcpu_nr_empty_pop_pages;
int pcpu_nr_empty_pop_pages[PCPU_NR_CHUNK_TYPES];
/*
* The number of populated pages in use by the allocator, protected by
@ -556,7 +556,7 @@ static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
{
chunk->nr_empty_pop_pages += nr;
if (chunk != pcpu_reserved_chunk)
pcpu_nr_empty_pop_pages += nr;
pcpu_nr_empty_pop_pages[pcpu_chunk_type(chunk)] += nr;
}
/*
@ -1832,7 +1832,7 @@ area_found:
mutex_unlock(&pcpu_alloc_mutex);
}
if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
if (pcpu_nr_empty_pop_pages[type] < PCPU_EMPTY_POP_PAGES_LOW)
pcpu_schedule_balance_work();
/* clear the areas and return address relative to base address */
@ -2000,7 +2000,7 @@ retry_pop:
pcpu_atomic_alloc_failed = false;
} else {
nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
pcpu_nr_empty_pop_pages,
pcpu_nr_empty_pop_pages[type],
0, PCPU_EMPTY_POP_PAGES_HIGH);
}
@ -2580,7 +2580,7 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
/* link the first chunk in */
pcpu_first_chunk = chunk;
pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
pcpu_nr_empty_pop_pages[PCPU_CHUNK_ROOT] = pcpu_first_chunk->nr_empty_pop_pages;
pcpu_chunk_relocate(pcpu_first_chunk, -1);
/* include all regions of the first chunk */