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author | Sean O. Stalley <sean.stalley@intel.com> | 2015-09-08 15:02:24 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-08 15:35:28 -0700 |
commit | fa23f56d90ed7bd760ae2aea6dfb2f501a099e90 (patch) | |
tree | 3c747a07b47354302ada3df61943552ce09815f8 | |
parent | c54839a722a02818677bcabe57e957f0ce4f841d (diff) | |
download | linux-stable-fa23f56d90ed7bd760ae2aea6dfb2f501a099e90.tar.gz linux-stable-fa23f56d90ed7bd760ae2aea6dfb2f501a099e90.tar.bz2 linux-stable-fa23f56d90ed7bd760ae2aea6dfb2f501a099e90.zip |
mm: add support for __GFP_ZERO flag to dma_pool_alloc()
Currently a call to dma_pool_alloc() with a ___GFP_ZERO flag returns a
non-zeroed memory region.
This patchset adds support for the __GFP_ZERO flag to dma_pool_alloc(),
adds 2 wrapper functions for allocing zeroed memory from a pool, and
provides a coccinelle script for finding & replacing instances of
dma_pool_alloc() followed by memset(0) with a single dma_pool_zalloc()
call.
There was some concern that this always calls memset() to zero, instead
of passing __GFP_ZERO into the page allocator.
[https://lkml.org/lkml/2015/7/15/881]
I ran a test on my system to get an idea of how often dma_pool_alloc()
calls into pool_alloc_page().
After Boot: [ 30.119863] alloc_calls:541, page_allocs:7
After an hour: [ 3600.951031] alloc_calls:9566, page_allocs:12
After copying 1GB file onto a USB drive:
[ 4260.657148] alloc_calls:17225, page_allocs:12
It doesn't look like dma_pool_alloc() calls down to the page allocator
very often (at least on my system).
This patch (of 4):
Currently the __GFP_ZERO flag is ignored by dma_pool_alloc().
Make dma_pool_alloc() zero the memory if this flag is set.
Signed-off-by: Sean O. Stalley <sean.stalley@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Gilles Muller <Gilles.Muller@lip6.fr>
Cc: Nicolas Palix <nicolas.palix@imag.fr>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | mm/dmapool.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/mm/dmapool.c b/mm/dmapool.c index 4b657099111f..71a8998cd03a 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -337,7 +337,7 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */ spin_unlock_irqrestore(&pool->lock, flags); - page = pool_alloc_page(pool, mem_flags); + page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO)); if (!page) return NULL; @@ -375,9 +375,14 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, break; } } - memset(retval, POOL_POISON_ALLOCATED, pool->size); + if (!(mem_flags & __GFP_ZERO)) + memset(retval, POOL_POISON_ALLOCATED, pool->size); #endif spin_unlock_irqrestore(&pool->lock, flags); + + if (mem_flags & __GFP_ZERO) + memset(retval, 0, pool->size); + return retval; } EXPORT_SYMBOL(dma_pool_alloc); |