From: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
To: Mike Kravetz <mike.kravetz@oracle.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Roman Gushchin <guro@fb.com>, Michal Hocko <mhocko@suse.com>,
Shakeel Butt <shakeelb@google.com>,
Oscar Salvador <osalvador@suse.de>,
David Hildenbrand <david@redhat.com>,
Muchun Song <songmuchun@bytedance.com>,
David Rientjes <rientjes@google.com>,
linmiaohe <linmiaohe@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
HORIGUCHI NAOYA <naoya.horiguchi@nec.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Waiman Long <longman@redhat.com>, Peter Xu <peterx@redhat.com>,
Mina Almasry <almasrymina@google.com>,
Hillf Danton <hdanton@sina.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Will Deacon <will@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: RE: [PATCH v2 1/8] mm/cma: change cma mutex to irq safe spinlock
Date: Tue, 30 Mar 2021 01:20:15 +0000 [thread overview]
Message-ID: <3de3a89983894cb79a0f25cf17e838f1@hisilicon.com> (raw)
In-Reply-To: <20210329232402.575396-2-mike.kravetz@oracle.com>
> -----Original Message-----
> From: Mike Kravetz [mailto:mike.kravetz@oracle.com]
> Sent: Tuesday, March 30, 2021 12:24 PM
> To: linux-mm@kvack.org; linux-kernel@vger.kernel.org
> Cc: Roman Gushchin <guro@fb.com>; Michal Hocko <mhocko@suse.com>; Shakeel Butt
> <shakeelb@google.com>; Oscar Salvador <osalvador@suse.de>; David Hildenbrand
> <david@redhat.com>; Muchun Song <songmuchun@bytedance.com>; David Rientjes
> <rientjes@google.com>; linmiaohe <linmiaohe@huawei.com>; Peter Zijlstra
> <peterz@infradead.org>; Matthew Wilcox <willy@infradead.org>; HORIGUCHI NAOYA
> <naoya.horiguchi@nec.com>; Aneesh Kumar K . V <aneesh.kumar@linux.ibm.com>;
> Waiman Long <longman@redhat.com>; Peter Xu <peterx@redhat.com>; Mina Almasry
> <almasrymina@google.com>; Hillf Danton <hdanton@sina.com>; Joonsoo Kim
> <iamjoonsoo.kim@lge.com>; Song Bao Hua (Barry Song)
> <song.bao.hua@hisilicon.com>; Will Deacon <will@kernel.org>; Andrew Morton
> <akpm@linux-foundation.org>; Mike Kravetz <mike.kravetz@oracle.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@oracle.com>
It seems mutex_lock is locking some areas with bitmap operations which
should be safe to atomic context.
Reviewed-by: Barry Song <song.bao.hua@hisilicon.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
next prev parent reply other threads:[~2021-03-30 1:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-29 23:23 [PATCH v2 0/8] make hugetlb put_page safe for all calling contexts Mike Kravetz
2021-03-29 23:23 ` [PATCH v2 1/8] mm/cma: change cma mutex to irq safe spinlock Mike Kravetz
2021-03-30 1:13 ` Roman Gushchin
2021-03-30 1:20 ` Song Bao Hua (Barry Song) [this message]
2021-03-30 2:18 ` Mike Kravetz
2021-03-30 8:01 ` Michal Hocko
2021-03-30 8:08 ` [External] " Muchun Song
2021-03-30 8:17 ` Song Bao Hua (Barry Song)
2021-03-30 8:18 ` Michal Hocko
2021-03-30 8:21 ` Muchun Song
2021-03-31 2:37 ` Mike Kravetz
2021-03-29 23:23 ` [PATCH v2 2/8] hugetlb: no need to drop hugetlb_lock to call cma_release Mike Kravetz
2021-03-30 1:13 ` Roman Gushchin
2021-03-30 8:01 ` Michal Hocko
2021-03-29 23:23 ` [PATCH v2 3/8] hugetlb: add per-hstate mutex to synchronize user adjustments Mike Kravetz
2021-03-30 2:23 ` [External] " Muchun Song
2021-03-29 23:23 ` [PATCH v2 4/8] hugetlb: create remove_hugetlb_page() to separate functionality Mike Kravetz
2021-03-29 23:23 ` [PATCH v2 5/8] hugetlb: call update_and_free_page without hugetlb_lock Mike Kravetz
2021-03-30 2:10 ` Miaohe Lin
2021-03-30 2:21 ` [External] " Muchun Song
2021-03-31 2:39 ` Mike Kravetz
2021-03-29 23:24 ` [PATCH v2 6/8] hugetlb: change free_pool_huge_page to remove_pool_huge_page Mike Kravetz
2021-03-30 2:30 ` [External] " Muchun Song
2021-03-30 8:06 ` Michal Hocko
2021-03-29 23:24 ` [PATCH v2 7/8] hugetlb: make free_huge_page irq safe Mike Kravetz
2021-03-29 23:24 ` [PATCH v2 8/8] hugetlb: add lockdep_assert_held() calls for hugetlb_lock Mike Kravetz
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