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percpu: allow select gfp to be passed to underlying allocators

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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>
This commit is contained in:
Dennis Zhou 2018-02-16 12:09:58 -06:00 committed by Tejun Heo
parent 47504ee04b
commit 554fef1c39
3 changed files with 10 additions and 12 deletions
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2
mm/percpu-km.c
View File

@ -56,7 +56,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
if (!chunk)
return NULL;
pages = alloc_pages(gfp | GFP_KERNEL, order_base_2(nr_pages));
pages = alloc_pages(gfp, order_base_2(nr_pages));
if (!pages) {
pcpu_free_chunk(chunk);
return NULL;

4
mm/percpu-vm.c
View File

@ -37,7 +37,7 @@ static struct page **pcpu_get_pages(void)
lockdep_assert_held(&pcpu_alloc_mutex);
if (!pages)
pages = pcpu_mem_zalloc(pages_size, 0);
pages = pcpu_mem_zalloc(pages_size, GFP_KERNEL);
return pages;
}
@ -86,7 +86,7 @@ static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
unsigned int cpu, tcpu;
int i;
gfp |= GFP_KERNEL | __GFP_HIGHMEM;
gfp |= __GFP_HIGHMEM;
for_each_possible_cpu(cpu) {
for (i = page_start; i < page_end; i++) {

16
mm/percpu.c
View File

@ -454,9 +454,6 @@ static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
* This is to facilitate passing through whitelisted flags. The
* returned memory is always zeroed.
*
* CONTEXT:
* Does GFP_KERNEL allocation.
*
* RETURNS:
* Pointer to the allocated area on success, NULL on failure.
*/
@ -466,10 +463,9 @@ static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
return NULL;
if (size <= PAGE_SIZE)
return kzalloc(size, gfp | GFP_KERNEL);
return kzalloc(size, gfp);
else
return __vmalloc(size, gfp | GFP_KERNEL | __GFP_ZERO,
PAGE_KERNEL);
return __vmalloc(size, gfp | __GFP_ZERO, PAGE_KERNEL);
}
/**
@ -1344,6 +1340,8 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
gfp_t gfp)
{
/* whitelisted flags that can be passed to the backing allocators */
gfp_t pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
bool do_warn = !(gfp & __GFP_NOWARN);
static int warn_limit = 10;
@ -1426,7 +1424,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
}
if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
chunk = pcpu_create_chunk(0);
chunk = pcpu_create_chunk(pcpu_gfp);
if (!chunk) {
err = "failed to allocate new chunk";
goto fail;
@ -1455,7 +1453,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
page_start, page_end) {
WARN_ON(chunk->immutable);
ret = pcpu_populate_chunk(chunk, rs, re, 0);
ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
spin_lock_irqsave(&pcpu_lock, flags);
if (ret) {
@ -1576,7 +1574,7 @@ void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
static void pcpu_balance_workfn(struct work_struct *work)
{
/* gfp flags passed to underlying allocators */
const gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
LIST_HEAD(to_free);
struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1];
struct pcpu_chunk *chunk, *next;