linux-hardened/mm/percpu-km.c
Dennis Zhou 554fef1c39 percpu: allow select gfp to be passed to underlying allocators
The prior patch added support for passing gfp flags through to the
underlying allocators. This patch allows users to pass along gfp flags
(currently only __GFP_NORETRY and __GFP_NOWARN) to the underlying
allocators. This should allow users to decide if they are ok with
failing allocations recovering in a more graceful way.

Additionally, gfp passing was done as additional flags in the previous
patch. Instead, change this to caller passed semantics. GFP_KERNEL is
also removed as the default flag. It continues to be used for internally
caused underlying percpu allocations.

V2:
Removed gfp_percpu_mask in favor of doing it inline.
Removed GFP_KERNEL as a default flag for __alloc_percpu_gfp.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2018-02-18 05:33:01 -08:00

119 lines
2.9 KiB
C

/*
* mm/percpu-km.c - kernel memory based chunk allocation
*
* Copyright (C) 2010 SUSE Linux Products GmbH
* Copyright (C) 2010 Tejun Heo <tj@kernel.org>
*
* This file is released under the GPLv2.
*
* Chunks are allocated as a contiguous kernel memory using gfp
* allocation. This is to be used on nommu architectures.
*
* To use percpu-km,
*
* - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
*
* - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's
* not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work
* fine.
*
* - NUMA is not supported. When setting up the first chunk,
* @cpu_distance_fn should be NULL or report all CPUs to be nearer
* than or at LOCAL_DISTANCE.
*
* - It's best if the chunk size is power of two multiple of
* PAGE_SIZE. Because each chunk is allocated as a contiguous
* kernel memory block using alloc_pages(), memory will be wasted if
* chunk size is not aligned. percpu-km code will whine about it.
*/
#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
#error "contiguous percpu allocation is incompatible with paged first chunk"
#endif
#include <linux/log2.h>
static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
int page_start, int page_end, gfp_t gfp)
{
return 0;
}
static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
int page_start, int page_end)
{
/* nada */
}
static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
{
const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
struct pcpu_chunk *chunk;
struct page *pages;
int i;
chunk = pcpu_alloc_chunk(gfp);
if (!chunk)
return NULL;
pages = alloc_pages(gfp, order_base_2(nr_pages));
if (!pages) {
pcpu_free_chunk(chunk);
return NULL;
}
for (i = 0; i < nr_pages; i++)
pcpu_set_page_chunk(nth_page(pages, i), chunk);
chunk->data = pages;
chunk->base_addr = page_address(pages) - pcpu_group_offsets[0];
spin_lock_irq(&pcpu_lock);
pcpu_chunk_populated(chunk, 0, nr_pages, false);
spin_unlock_irq(&pcpu_lock);
pcpu_stats_chunk_alloc();
trace_percpu_create_chunk(chunk->base_addr);
return chunk;
}
static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
{
const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
if (!chunk)
return;
pcpu_stats_chunk_dealloc();
trace_percpu_destroy_chunk(chunk->base_addr);
if (chunk->data)
__free_pages(chunk->data, order_base_2(nr_pages));
pcpu_free_chunk(chunk);
}
static struct page *pcpu_addr_to_page(void *addr)
{
return virt_to_page(addr);
}
static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
{
size_t nr_pages, alloc_pages;
/* all units must be in a single group */
if (ai->nr_groups != 1) {
pr_crit("can't handle more than one group\n");
return -EINVAL;
}
nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
alloc_pages = roundup_pow_of_two(nr_pages);
if (alloc_pages > nr_pages)
pr_warn("wasting %zu pages per chunk\n",
alloc_pages - nr_pages);
return 0;
}