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 <dennissz...@gmail.com>
Suggested-by: Daniel Borkmann <dan...@iogearbox.net>
---
mm/percpu-km.c | 2 +-
mm/percpu-vm.c | 4 ++--
mm/percpu.c | 16 +++++++---------
3 files changed, 10 insertions(+), 12 deletions(-)
diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index 0d88d7b..38de70a 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -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;
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index 0af71eb..d8078de 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -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++) {
diff --git a/mm/percpu.c b/mm/percpu.c
index f97443d..fa3f854 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -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;
--
1.8.3.1
