| Message ID | 20210331034148.112624-2-mike.kravetz@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | make hugetlb put_page safe for all calling contexts | expand |
On Tue 30-03-21 20:41:41, Mike Kravetz wrote: > cma_release is currently a sleepable operatation because the bitmap > manipulation is protected by cma->lock mutex. Hugetlb code which relies > on cma_release for CMA backed (giga) hugetlb pages, however, needs to be > irq safe. > > The lock doesn't protect any sleepable operation so it can be changed to > a (irq aware) spin lock. The bitmap processing should be quite fast in > typical case but if cma sizes grow to TB then we will likely need to > replace the lock by a more optimized bitmap implementation. > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/cma.c | 18 +++++++++--------- > mm/cma.h | 2 +- > mm/cma_debug.c | 8 ++++---- > 3 files changed, 14 insertions(+), 14 deletions(-) > > diff --git a/mm/cma.c b/mm/cma.c > index b2393b892d3b..2380f2571eb5 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); > @@ -392,7 +392,7 @@ static void cma_debug_show_areas(struct cma *cma) > unsigned long nr_part, nr_total = 0; > unsigned long nbits = cma_bitmap_maxno(cma); > > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > pr_info("number of available pages: "); > for (;;) { > next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start); > @@ -407,7 +407,7 @@ 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_irq(&cma->lock); > } > #else > static inline void cma_debug_show_areas(struct cma *cma) { } > @@ -454,12 +454,12 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, > goto out; > > for (;;) { > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > 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_irq(&cma->lock); > break; > } > bitmap_set(cma->bitmap, bitmap_no, bitmap_count); > @@ -468,7 +468,7 @@ 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_irq(&cma->lock); > > 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..2e7704955f4f 100644 > --- a/mm/cma_debug.c > +++ b/mm/cma_debug.c > @@ -36,10 +36,10 @@ static int cma_used_get(void *data, u64 *val) > struct cma *cma = data; > unsigned long used; > > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > /* pages counter is smaller than sizeof(int) */ > used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma)); > - mutex_unlock(&cma->lock); > + spin_unlock_irq(&cma->lock); > *val = (u64)used << cma->order_per_bit; > > return 0; > @@ -53,7 +53,7 @@ static int cma_maxchunk_get(void *data, u64 *val) > unsigned long start, end = 0; > unsigned long bitmap_maxno = cma_bitmap_maxno(cma); > > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > for (;;) { > start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end); > if (start >= bitmap_maxno) > @@ -61,7 +61,7 @@ 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_irq(&cma->lock); > *val = (u64)maxchunk << cma->order_per_bit; > > return 0; > -- > 2.30.2 >
On 31.03.21 05:41, Mike Kravetz wrote: > cma_release is currently a sleepable operatation because the bitmap > manipulation is protected by cma->lock mutex. Hugetlb code which relies > on cma_release for CMA backed (giga) hugetlb pages, however, needs to be > irq safe. > > The lock doesn't protect any sleepable operation so it can be changed to > a (irq aware) spin lock. The bitmap processing should be quite fast in > typical case but if cma sizes grow to TB then we will likely need to > replace the lock by a more optimized bitmap implementation. > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > --- > mm/cma.c | 18 +++++++++--------- > mm/cma.h | 2 +- > mm/cma_debug.c | 8 ++++---- > 3 files changed, 14 insertions(+), 14 deletions(-) > > diff --git a/mm/cma.c b/mm/cma.c > index b2393b892d3b..2380f2571eb5 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); > @@ -392,7 +392,7 @@ static void cma_debug_show_areas(struct cma *cma) > unsigned long nr_part, nr_total = 0; > unsigned long nbits = cma_bitmap_maxno(cma); > > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > pr_info("number of available pages: "); > for (;;) { > next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start); > @@ -407,7 +407,7 @@ 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_irq(&cma->lock); > } > #else > static inline void cma_debug_show_areas(struct cma *cma) { } > @@ -454,12 +454,12 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, > goto out; > > for (;;) { > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > 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_irq(&cma->lock); > break; > } > bitmap_set(cma->bitmap, bitmap_no, bitmap_count); > @@ -468,7 +468,7 @@ 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_irq(&cma->lock); > > 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..2e7704955f4f 100644 > --- a/mm/cma_debug.c > +++ b/mm/cma_debug.c > @@ -36,10 +36,10 @@ static int cma_used_get(void *data, u64 *val) > struct cma *cma = data; > unsigned long used; > > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > /* pages counter is smaller than sizeof(int) */ > used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma)); > - mutex_unlock(&cma->lock); > + spin_unlock_irq(&cma->lock); > *val = (u64)used << cma->order_per_bit; > > return 0; > @@ -53,7 +53,7 @@ static int cma_maxchunk_get(void *data, u64 *val) > unsigned long start, end = 0; > unsigned long bitmap_maxno = cma_bitmap_maxno(cma); > > - mutex_lock(&cma->lock); > + spin_lock_irq(&cma->lock); > for (;;) { > start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end); > if (start >= bitmap_maxno) > @@ -61,7 +61,7 @@ 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_irq(&cma->lock); > *val = (u64)maxchunk << cma->order_per_bit; > > return 0; > Reviewed-by: David Hildenbrand <david@redhat.com>
diff --git a/mm/cma.c b/mm/cma.c index b2393b892d3b..2380f2571eb5 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); @@ -392,7 +392,7 @@ static void cma_debug_show_areas(struct cma *cma) unsigned long nr_part, nr_total = 0; unsigned long nbits = cma_bitmap_maxno(cma); - mutex_lock(&cma->lock); + spin_lock_irq(&cma->lock); pr_info("number of available pages: "); for (;;) { next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start); @@ -407,7 +407,7 @@ 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_irq(&cma->lock); } #else static inline void cma_debug_show_areas(struct cma *cma) { } @@ -454,12 +454,12 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, goto out; for (;;) { - mutex_lock(&cma->lock); + spin_lock_irq(&cma->lock); 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_irq(&cma->lock); break; } bitmap_set(cma->bitmap, bitmap_no, bitmap_count); @@ -468,7 +468,7 @@ 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_irq(&cma->lock); 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..2e7704955f4f 100644 --- a/mm/cma_debug.c +++ b/mm/cma_debug.c @@ -36,10 +36,10 @@ static int cma_used_get(void *data, u64 *val) struct cma *cma = data; unsigned long used; - mutex_lock(&cma->lock); + spin_lock_irq(&cma->lock); /* pages counter is smaller than sizeof(int) */ used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma)); - mutex_unlock(&cma->lock); + spin_unlock_irq(&cma->lock); *val = (u64)used << cma->order_per_bit; return 0; @@ -53,7 +53,7 @@ static int cma_maxchunk_get(void *data, u64 *val) unsigned long start, end = 0; unsigned long bitmap_maxno = cma_bitmap_maxno(cma); - mutex_lock(&cma->lock); + spin_lock_irq(&cma->lock); for (;;) { start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end); if (start >= bitmap_maxno) @@ -61,7 +61,7 @@ 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_irq(&cma->lock); *val = (u64)maxchunk << cma->order_per_bit; return 0;
cma_release is currently a sleepable operatation because the bitmap manipulation is protected by cma->lock mutex. Hugetlb code which relies on cma_release for CMA backed (giga) hugetlb pages, however, needs to be irq safe. The lock doesn't protect any sleepable operation so it can be changed to a (irq aware) spin lock. The bitmap processing should be quite fast in typical case but if cma sizes grow to TB then we will likely need to replace the lock by a more optimized bitmap implementation. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> --- mm/cma.c | 18 +++++++++--------- mm/cma.h | 2 +- mm/cma_debug.c | 8 ++++---- 3 files changed, 14 insertions(+), 14 deletions(-)