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mm/cma: support cma inactive feature

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When do active cma area, the reserved blocks from cma area will be
insert into system memory, and the pages will be allocated first even
then the system freelist is not empty.

After system borrows pages from cma, the cma will do isolate/migrate
them when the cma alloc happens, that spends much time and sometimes the
pages are pinned result a page busy failure.

This patch adds a CONFIG_CMA_INACTIVE to give a option, allows the cma
area not active and then system can not borrows pages from cma.

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Change-Id: Iaaece4abda1ed0250e603e9255a59ebfa5c3a65f
This commit is contained in:
Jianqun Xu
2022-03-24 17:49:08 +08:00
committed by Tao Huang
parent 53be42237a
commit 87e8391b85
2 changed files with 19 additions and 2 deletions
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9
mm/Kconfig
View File

@@ -505,6 +505,15 @@ config CMA
If unsure, say "n".
config CMA_INACTIVE
bool "CMA not active to system"
depends on CMA
help
This forbids the CMA to active its pages to system memory, to keep
page from CMA never be borrowed by system.
If unsure, say "n".
config CMA_DEBUG
bool "CMA debug messages (DEVELOPMENT)"
depends on DEBUG_KERNEL && CMA

12
mm/cma.c
View File

@@ -111,6 +111,8 @@ static void __init cma_activate_area(struct cma *cma)
if (!cma->bitmap)
goto out_error;
if (IS_ENABLED(CONFIG_CMA_INACTIVE))
goto out;
/*
* alloc_contig_range() requires the pfn range specified to be in the
* same zone. Simplify by forcing the entire CMA resv range to be in the
@@ -128,6 +130,7 @@ static void __init cma_activate_area(struct cma *cma)
pfn += pageblock_nr_pages)
init_cma_reserved_pageblock(pfn_to_page(pfn));
out:
mutex_init(&cma->lock);
#ifdef CONFIG_CMA_DEBUGFS
@@ -511,6 +514,11 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
mutex_unlock(&cma->lock);
pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
if (IS_ENABLED(CONFIG_CMA_INACTIVE)) {
page = pfn_to_page(pfn);
lru_cache_enable();
goto out;
}
ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA, gfp_mask, &info);
cma_info.nr_migrated += info.nr_migrated;
cma_info.nr_reclaimed += info.nr_reclaimed;
@@ -610,8 +618,8 @@ bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
return false;
VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
free_contig_range(pfn, count);
if (!IS_ENABLED(CONFIG_CMA_INACTIVE))
free_contig_range(pfn, count);
cma_clear_bitmap(cma, pfn, count);
trace_cma_release(cma->name, pfn, pages, count);