From 14f162cb64a8beca59f06cd94d5569bd550dc99d Mon Sep 17 00:00:00 2001 From: Mitchel Humpherys Date: Tue, 6 Aug 2013 15:08:23 -0700 Subject: [PATCH] ion: Add private buffer flag to skip page pooling on free Currently, when we free a buffer it might actually just go back into a heap-specific page pool rather than going back to the system. This poses a problem because sometimes (like when we're running a shrinker in low memory conditions) we need to force the memory associated with the buffer to truly be relinquished to the system rather than just going back into a page pool. There isn't a use case for this flag by Ion clients, so make it a private flag. The main use case right now is to provide a mechanism for the deferred free code to force stale buffers to bypass page pooling. Change-Id: I724f89cc037083fe8576784363caa18a34e8705a Signed-off-by: Mitchel Humpherys --- drivers/staging/android/ion/ion_heap.c | 19 +++++++-- drivers/staging/android/ion/ion_priv.h | 42 ++++++++++++++++++- drivers/staging/android/ion/ion_system_heap.c | 4 +- 3 files changed, 59 insertions(+), 6 deletions(-) diff --git a/drivers/staging/android/ion/ion_heap.c b/drivers/staging/android/ion/ion_heap.c index 5c14bc2a1822..750b76af0cf3 100644 --- a/drivers/staging/android/ion/ion_heap.c +++ b/drivers/staging/android/ion/ion_heap.c @@ -178,7 +178,8 @@ size_t ion_heap_freelist_size(struct ion_heap *heap) return size; } -size_t ion_heap_freelist_drain(struct ion_heap *heap, size_t size) +static size_t _ion_heap_freelist_drain(struct ion_heap *heap, size_t size, + bool skip_pools) { struct ion_buffer *buffer; size_t total_drained = 0; @@ -197,6 +198,8 @@ size_t ion_heap_freelist_drain(struct ion_heap *heap, size_t size) list); list_del(&buffer->list); heap->free_list_size -= buffer->size; + if (skip_pools) + buffer->private_flags |= ION_PRIV_FLAG_SHRINKER_FREE; total_drained += buffer->size; spin_unlock(&heap->free_lock); ion_buffer_destroy(buffer); @@ -207,6 +210,16 @@ size_t ion_heap_freelist_drain(struct ion_heap *heap, size_t size) return total_drained; } +size_t ion_heap_freelist_drain(struct ion_heap *heap, size_t size) +{ + return _ion_heap_freelist_drain(heap, size, false); +} + +size_t ion_heap_freelist_shrink(struct ion_heap *heap, size_t size) +{ + return _ion_heap_freelist_drain(heap, size, true); +} + static int ion_heap_deferred_free(void *data) { struct ion_heap *heap = data; @@ -265,10 +278,10 @@ static int ion_heap_shrink(struct shrinker *shrinker, struct shrink_control *sc) /* * shrink the free list first, no point in zeroing the memory if we're - * just going to reclaim it + * just going to reclaim it. Also, skip any possible page pooling. */ if (heap->flags & ION_HEAP_FLAG_DEFER_FREE) - freed = ion_heap_freelist_drain(heap, to_scan * PAGE_SIZE) / + freed = ion_heap_freelist_shrink(heap, to_scan * PAGE_SIZE) / PAGE_SIZE; to_scan -= freed; diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h index 85866e6d2f92..18ef365e7552 100644 --- a/drivers/staging/android/ion/ion_priv.h +++ b/drivers/staging/android/ion/ion_priv.h @@ -38,6 +38,7 @@ struct ion_buffer *ion_handle_buffer(struct ion_handle *handle); * @dev: back pointer to the ion_device * @heap: back pointer to the heap the buffer came from * @flags: buffer specific flags + * @private_flags: internal buffer specific flags * @size: size of the buffer * @priv_virt: private data to the buffer representable as * a void * @@ -66,6 +67,7 @@ struct ion_buffer { struct ion_device *dev; struct ion_heap *heap; unsigned long flags; + unsigned long private_flags; size_t size; union { void *priv_virt; @@ -98,7 +100,11 @@ void ion_buffer_destroy(struct ion_buffer *buffer); * @map_user map memory to userspace * * allocate, phys, and map_user return 0 on success, -errno on error. - * map_dma and map_kernel return pointer on success, ERR_PTR on error. + * map_dma and map_kernel return pointer on success, ERR_PTR on + * error. @free will be called with ION_PRIV_FLAG_SHRINKER_FREE set in + * the buffer's private_flags when called from a shrinker. In that + * case, the pages being free'd must be truly free'd back to the + * system, not put in a page pool or otherwise cached. */ struct ion_heap_ops { int (*allocate) (struct ion_heap *heap, @@ -122,6 +128,17 @@ struct ion_heap_ops { */ #define ION_HEAP_FLAG_DEFER_FREE (1 << 0) +/** + * private flags - flags internal to ion + */ +/* + * Buffer is being freed from a shrinker function. Skip any possible + * heap-specific caching mechanism (e.g. page pools). Guarantees that + * any buffer storage that came from the system allocator will be + * returned to the system allocator. + */ +#define ION_PRIV_FLAG_SHRINKER_FREE (1 << 0) + /** * struct ion_heap - represents a heap in the system * @node: rb node to put the heap on the device's tree of heaps @@ -257,6 +274,29 @@ void ion_heap_freelist_add(struct ion_heap *heap, struct ion_buffer *buffer); */ size_t ion_heap_freelist_drain(struct ion_heap *heap, size_t size); +/** + * ion_heap_freelist_shrink - drain the deferred free + * list, skipping any heap-specific + * pooling or caching mechanisms + * + * @heap: the heap + * @size: amount of memory to drain in bytes + * + * Drains the indicated amount of memory from the deferred freelist immediately. + * Returns the total amount freed. The total freed may be higher depending + * on the size of the items in the list, or lower if there is insufficient + * total memory on the freelist. + * + * Unlike with @ion_heap_freelist_drain, don't put any pages back into + * page pools or otherwise cache the pages. Everything must be + * genuinely free'd back to the system. If you're free'ing from a + * shrinker you probably want to use this. Note that this relies on + * the heap.ops.free callback honoring the ION_PRIV_FLAG_SHRINKER_FREE + * flag. + */ +size_t ion_heap_freelist_shrink(struct ion_heap *heap, + size_t size); + /** * ion_heap_freelist_size - returns the size of the freelist in bytes * @heap: the heap diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c index 4a87fcf53266..a2c8968104f8 100644 --- a/drivers/staging/android/ion/ion_system_heap.c +++ b/drivers/staging/android/ion/ion_system_heap.c @@ -90,7 +90,7 @@ static void free_buffer_page(struct ion_system_heap *heap, { bool cached = ion_buffer_cached(buffer); - if (!cached) { + if (!cached && !(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)) { struct ion_page_pool *pool = heap->pools[order_to_index(order)]; ion_page_pool_free(pool, page); } else { @@ -205,7 +205,7 @@ static void ion_system_heap_free(struct ion_buffer *buffer) /* uncached pages come from the page pools, zero them before returning for security purposes (other allocations are zerod at alloc time */ - if (!cached) + if (!cached && !(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)) ion_heap_buffer_zero(buffer); for_each_sg(table->sgl, sg, table->nents, i) -- 2.34.1