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Date: Mon, 29 Mar 2021 16:23:55 -0700
From: Mike Kravetz <mike.kravetz@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: Roman Gushchin <guro@...com>, Michal Hocko <mhocko@...e.com>,
Shakeel Butt <shakeelb@...gle.com>,
Oscar Salvador <osalvador@...e.de>,
David Hildenbrand <david@...hat.com>,
Muchun Song <songmuchun@...edance.com>,
David Rientjes <rientjes@...gle.com>,
Miaohe Lin <linmiaohe@...wei.com>,
Peter Zijlstra <peterz@...radead.org>,
Matthew Wilcox <willy@...radead.org>,
HORIGUCHI NAOYA <naoya.horiguchi@....com>,
"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
Waiman Long <longman@...hat.com>, Peter Xu <peterx@...hat.com>,
Mina Almasry <almasrymina@...gle.com>,
Hillf Danton <hdanton@...a.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Barry Song <song.bao.hua@...ilicon.com>,
Will Deacon <will@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Kravetz <mike.kravetz@...cle.com>
Subject: [PATCH v2 1/8] mm/cma: change cma mutex to irq safe spinlock
Ideally, cma_release could be called from any context. However, that is
not possible because a mutex is used to protect the per-area bitmap.
Change the bitmap to an irq safe spinlock.
Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
---
mm/cma.c | 20 +++++++++++---------
mm/cma.h | 2 +-
mm/cma_debug.c | 10 ++++++----
3 files changed, 18 insertions(+), 14 deletions(-)
diff --git a/mm/cma.c b/mm/cma.c
index b2393b892d3b..80875fd4487b 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -24,7 +24,6 @@
#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/mm.h>
-#include <linux/mutex.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/log2.h>
@@ -83,13 +82,14 @@ static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
unsigned int count)
{
unsigned long bitmap_no, bitmap_count;
+ unsigned long flags;
bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
bitmap_count = cma_bitmap_pages_to_bits(cma, count);
- mutex_lock(&cma->lock);
+ spin_lock_irqsave(&cma->lock, flags);
bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
- mutex_unlock(&cma->lock);
+ spin_unlock_irqrestore(&cma->lock, flags);
}
static void __init cma_activate_area(struct cma *cma)
@@ -118,7 +118,7 @@ static void __init cma_activate_area(struct cma *cma)
pfn += pageblock_nr_pages)
init_cma_reserved_pageblock(pfn_to_page(pfn));
- mutex_init(&cma->lock);
+ spin_lock_init(&cma->lock);
#ifdef CONFIG_CMA_DEBUGFS
INIT_HLIST_HEAD(&cma->mem_head);
@@ -391,8 +391,9 @@ static void cma_debug_show_areas(struct cma *cma)
unsigned long start = 0;
unsigned long nr_part, nr_total = 0;
unsigned long nbits = cma_bitmap_maxno(cma);
+ unsigned long flags;
- mutex_lock(&cma->lock);
+ spin_lock_irqsave(&cma->lock, flags);
pr_info("number of available pages: ");
for (;;) {
next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start);
@@ -407,7 +408,7 @@ static void cma_debug_show_areas(struct cma *cma)
start = next_zero_bit + nr_zero;
}
pr_cont("=> %lu free of %lu total pages\n", nr_total, cma->count);
- mutex_unlock(&cma->lock);
+ spin_unlock_irqrestore(&cma->lock, flags);
}
#else
static inline void cma_debug_show_areas(struct cma *cma) { }
@@ -430,6 +431,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
unsigned long pfn = -1;
unsigned long start = 0;
unsigned long bitmap_maxno, bitmap_no, bitmap_count;
+ unsigned long flags;
size_t i;
struct page *page = NULL;
int ret = -ENOMEM;
@@ -454,12 +456,12 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
goto out;
for (;;) {
- mutex_lock(&cma->lock);
+ spin_lock_irqsave(&cma->lock, flags);
bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
bitmap_maxno, start, bitmap_count, mask,
offset);
if (bitmap_no >= bitmap_maxno) {
- mutex_unlock(&cma->lock);
+ spin_unlock_irqrestore(&cma->lock, flags);
break;
}
bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
@@ -468,7 +470,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
* our exclusive use. If the migration fails we will take the
* lock again and unmark it.
*/
- mutex_unlock(&cma->lock);
+ spin_unlock_irqrestore(&cma->lock, flags);
pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA,
diff --git a/mm/cma.h b/mm/cma.h
index 68ffad4e430d..2c775877eae2 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -15,7 +15,7 @@ struct cma {
unsigned long count;
unsigned long *bitmap;
unsigned int order_per_bit; /* Order of pages represented by one bit */
- struct mutex lock;
+ spinlock_t lock;
#ifdef CONFIG_CMA_DEBUGFS
struct hlist_head mem_head;
spinlock_t mem_head_lock;
diff --git a/mm/cma_debug.c b/mm/cma_debug.c
index d5bf8aa34fdc..6379cfbfd568 100644
--- a/mm/cma_debug.c
+++ b/mm/cma_debug.c
@@ -35,11 +35,12 @@ static int cma_used_get(void *data, u64 *val)
{
struct cma *cma = data;
unsigned long used;
+ unsigned long flags;
- mutex_lock(&cma->lock);
+ spin_lock_irqsave(&cma->lock, flags);
/* pages counter is smaller than sizeof(int) */
used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));
- mutex_unlock(&cma->lock);
+ spin_unlock_irqrestore(&cma->lock, flags);
*val = (u64)used << cma->order_per_bit;
return 0;
@@ -52,8 +53,9 @@ static int cma_maxchunk_get(void *data, u64 *val)
unsigned long maxchunk = 0;
unsigned long start, end = 0;
unsigned long bitmap_maxno = cma_bitmap_maxno(cma);
+ unsigned long flags;
- mutex_lock(&cma->lock);
+ spin_lock_irqsave(&cma->lock, flags);
for (;;) {
start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end);
if (start >= bitmap_maxno)
@@ -61,7 +63,7 @@ static int cma_maxchunk_get(void *data, u64 *val)
end = find_next_bit(cma->bitmap, bitmap_maxno, start);
maxchunk = max(end - start, maxchunk);
}
- mutex_unlock(&cma->lock);
+ spin_unlock_irqrestore(&cma->lock, flags);
*val = (u64)maxchunk << cma->order_per_bit;
return 0;
--
2.30.2
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