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![Mel Gorman](/assets/img/avatar_default.png)
__GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
537 lines
14 KiB
C
537 lines
14 KiB
C
/*
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* DMA Pool allocator
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*
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* Copyright 2001 David Brownell
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* Copyright 2007 Intel Corporation
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* Author: Matthew Wilcox <willy@linux.intel.com>
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*
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* This software may be redistributed and/or modified under the terms of
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* the GNU General Public License ("GPL") version 2 as published by the
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* Free Software Foundation.
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*
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* This allocator returns small blocks of a given size which are DMA-able by
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* the given device. It uses the dma_alloc_coherent page allocator to get
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* new pages, then splits them up into blocks of the required size.
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* Many older drivers still have their own code to do this.
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*
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* The current design of this allocator is fairly simple. The pool is
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* represented by the 'struct dma_pool' which keeps a doubly-linked list of
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* allocated pages. Each page in the page_list is split into blocks of at
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* least 'size' bytes. Free blocks are tracked in an unsorted singly-linked
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* list of free blocks within the page. Used blocks aren't tracked, but we
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* keep a count of how many are currently allocated from each page.
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*/
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#include <linux/device.h>
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#include <linux/dma-mapping.h>
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#include <linux/dmapool.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/export.h>
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#include <linux/mutex.h>
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#include <linux/poison.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/wait.h>
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#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
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#define DMAPOOL_DEBUG 1
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#endif
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struct dma_pool { /* the pool */
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struct list_head page_list;
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spinlock_t lock;
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size_t size;
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struct device *dev;
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size_t allocation;
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size_t boundary;
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char name[32];
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struct list_head pools;
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};
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struct dma_page { /* cacheable header for 'allocation' bytes */
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struct list_head page_list;
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void *vaddr;
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dma_addr_t dma;
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unsigned int in_use;
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unsigned int offset;
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};
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static DEFINE_MUTEX(pools_lock);
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static DEFINE_MUTEX(pools_reg_lock);
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static ssize_t
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show_pools(struct device *dev, struct device_attribute *attr, char *buf)
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{
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unsigned temp;
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unsigned size;
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char *next;
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struct dma_page *page;
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struct dma_pool *pool;
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next = buf;
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size = PAGE_SIZE;
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temp = scnprintf(next, size, "poolinfo - 0.1\n");
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size -= temp;
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next += temp;
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mutex_lock(&pools_lock);
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list_for_each_entry(pool, &dev->dma_pools, pools) {
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unsigned pages = 0;
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unsigned blocks = 0;
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spin_lock_irq(&pool->lock);
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list_for_each_entry(page, &pool->page_list, page_list) {
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pages++;
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blocks += page->in_use;
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}
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spin_unlock_irq(&pool->lock);
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/* per-pool info, no real statistics yet */
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temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
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pool->name, blocks,
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pages * (pool->allocation / pool->size),
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pool->size, pages);
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size -= temp;
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next += temp;
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}
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mutex_unlock(&pools_lock);
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return PAGE_SIZE - size;
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}
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static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
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/**
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* dma_pool_create - Creates a pool of consistent memory blocks, for dma.
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* @name: name of pool, for diagnostics
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* @dev: device that will be doing the DMA
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* @size: size of the blocks in this pool.
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* @align: alignment requirement for blocks; must be a power of two
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* @boundary: returned blocks won't cross this power of two boundary
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* Context: !in_interrupt()
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*
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* Returns a dma allocation pool with the requested characteristics, or
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* null if one can't be created. Given one of these pools, dma_pool_alloc()
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* may be used to allocate memory. Such memory will all have "consistent"
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* DMA mappings, accessible by the device and its driver without using
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* cache flushing primitives. The actual size of blocks allocated may be
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* larger than requested because of alignment.
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*
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* If @boundary is nonzero, objects returned from dma_pool_alloc() won't
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* cross that size boundary. This is useful for devices which have
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* addressing restrictions on individual DMA transfers, such as not crossing
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* boundaries of 4KBytes.
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*/
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struct dma_pool *dma_pool_create(const char *name, struct device *dev,
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size_t size, size_t align, size_t boundary)
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{
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struct dma_pool *retval;
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size_t allocation;
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bool empty = false;
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if (align == 0)
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align = 1;
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else if (align & (align - 1))
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return NULL;
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if (size == 0)
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return NULL;
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else if (size < 4)
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size = 4;
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if ((size % align) != 0)
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size = ALIGN(size, align);
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allocation = max_t(size_t, size, PAGE_SIZE);
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if (!boundary)
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boundary = allocation;
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else if ((boundary < size) || (boundary & (boundary - 1)))
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return NULL;
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retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
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if (!retval)
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return retval;
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strlcpy(retval->name, name, sizeof(retval->name));
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retval->dev = dev;
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INIT_LIST_HEAD(&retval->page_list);
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spin_lock_init(&retval->lock);
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retval->size = size;
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retval->boundary = boundary;
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retval->allocation = allocation;
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INIT_LIST_HEAD(&retval->pools);
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/*
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* pools_lock ensures that the ->dma_pools list does not get corrupted.
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* pools_reg_lock ensures that there is not a race between
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* dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
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* when the first invocation of dma_pool_create() failed on
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* device_create_file() and the second assumes that it has been done (I
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* know it is a short window).
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*/
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mutex_lock(&pools_reg_lock);
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mutex_lock(&pools_lock);
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if (list_empty(&dev->dma_pools))
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empty = true;
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list_add(&retval->pools, &dev->dma_pools);
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mutex_unlock(&pools_lock);
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if (empty) {
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int err;
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err = device_create_file(dev, &dev_attr_pools);
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if (err) {
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mutex_lock(&pools_lock);
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list_del(&retval->pools);
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mutex_unlock(&pools_lock);
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mutex_unlock(&pools_reg_lock);
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kfree(retval);
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return NULL;
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}
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}
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mutex_unlock(&pools_reg_lock);
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return retval;
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}
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EXPORT_SYMBOL(dma_pool_create);
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static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
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{
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unsigned int offset = 0;
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unsigned int next_boundary = pool->boundary;
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do {
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unsigned int next = offset + pool->size;
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if (unlikely((next + pool->size) >= next_boundary)) {
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next = next_boundary;
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next_boundary += pool->boundary;
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}
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*(int *)(page->vaddr + offset) = next;
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offset = next;
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} while (offset < pool->allocation);
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}
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static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
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{
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struct dma_page *page;
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page = kmalloc(sizeof(*page), mem_flags);
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if (!page)
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return NULL;
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page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
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&page->dma, mem_flags);
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if (page->vaddr) {
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#ifdef DMAPOOL_DEBUG
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memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
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#endif
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pool_initialise_page(pool, page);
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page->in_use = 0;
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page->offset = 0;
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} else {
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kfree(page);
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page = NULL;
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}
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return page;
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}
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static inline bool is_page_busy(struct dma_page *page)
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{
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return page->in_use != 0;
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}
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static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
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{
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dma_addr_t dma = page->dma;
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#ifdef DMAPOOL_DEBUG
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memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
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#endif
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dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
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list_del(&page->page_list);
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kfree(page);
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}
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/**
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* dma_pool_destroy - destroys a pool of dma memory blocks.
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* @pool: dma pool that will be destroyed
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* Context: !in_interrupt()
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*
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* Caller guarantees that no more memory from the pool is in use,
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* and that nothing will try to use the pool after this call.
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*/
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void dma_pool_destroy(struct dma_pool *pool)
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{
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bool empty = false;
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if (unlikely(!pool))
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return;
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mutex_lock(&pools_reg_lock);
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mutex_lock(&pools_lock);
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list_del(&pool->pools);
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if (pool->dev && list_empty(&pool->dev->dma_pools))
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empty = true;
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mutex_unlock(&pools_lock);
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if (empty)
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device_remove_file(pool->dev, &dev_attr_pools);
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mutex_unlock(&pools_reg_lock);
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while (!list_empty(&pool->page_list)) {
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struct dma_page *page;
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page = list_entry(pool->page_list.next,
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struct dma_page, page_list);
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if (is_page_busy(page)) {
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if (pool->dev)
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dev_err(pool->dev,
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"dma_pool_destroy %s, %p busy\n",
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pool->name, page->vaddr);
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else
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printk(KERN_ERR
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"dma_pool_destroy %s, %p busy\n",
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pool->name, page->vaddr);
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/* leak the still-in-use consistent memory */
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list_del(&page->page_list);
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kfree(page);
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} else
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pool_free_page(pool, page);
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}
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kfree(pool);
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}
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EXPORT_SYMBOL(dma_pool_destroy);
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/**
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* dma_pool_alloc - get a block of consistent memory
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* @pool: dma pool that will produce the block
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* @mem_flags: GFP_* bitmask
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* @handle: pointer to dma address of block
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*
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* This returns the kernel virtual address of a currently unused block,
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* and reports its dma address through the handle.
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* If such a memory block can't be allocated, %NULL is returned.
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*/
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void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
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dma_addr_t *handle)
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{
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unsigned long flags;
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struct dma_page *page;
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size_t offset;
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void *retval;
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might_sleep_if(gfpflags_allow_blocking(mem_flags));
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spin_lock_irqsave(&pool->lock, flags);
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list_for_each_entry(page, &pool->page_list, page_list) {
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if (page->offset < pool->allocation)
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goto ready;
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}
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/* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
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spin_unlock_irqrestore(&pool->lock, flags);
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page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
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if (!page)
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return NULL;
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spin_lock_irqsave(&pool->lock, flags);
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list_add(&page->page_list, &pool->page_list);
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ready:
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page->in_use++;
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offset = page->offset;
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page->offset = *(int *)(page->vaddr + offset);
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retval = offset + page->vaddr;
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*handle = offset + page->dma;
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#ifdef DMAPOOL_DEBUG
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{
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int i;
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u8 *data = retval;
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/* page->offset is stored in first 4 bytes */
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for (i = sizeof(page->offset); i < pool->size; i++) {
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if (data[i] == POOL_POISON_FREED)
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continue;
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if (pool->dev)
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dev_err(pool->dev,
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"dma_pool_alloc %s, %p (corrupted)\n",
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pool->name, retval);
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else
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pr_err("dma_pool_alloc %s, %p (corrupted)\n",
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pool->name, retval);
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/*
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* Dump the first 4 bytes even if they are not
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* POOL_POISON_FREED
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*/
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print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
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data, pool->size, 1);
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break;
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}
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}
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if (!(mem_flags & __GFP_ZERO))
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memset(retval, POOL_POISON_ALLOCATED, pool->size);
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#endif
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spin_unlock_irqrestore(&pool->lock, flags);
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if (mem_flags & __GFP_ZERO)
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memset(retval, 0, pool->size);
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return retval;
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}
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EXPORT_SYMBOL(dma_pool_alloc);
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static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
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{
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struct dma_page *page;
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list_for_each_entry(page, &pool->page_list, page_list) {
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if (dma < page->dma)
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continue;
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if ((dma - page->dma) < pool->allocation)
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return page;
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}
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return NULL;
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}
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/**
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* dma_pool_free - put block back into dma pool
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* @pool: the dma pool holding the block
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* @vaddr: virtual address of block
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* @dma: dma address of block
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*
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* Caller promises neither device nor driver will again touch this block
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* unless it is first re-allocated.
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*/
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void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
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{
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struct dma_page *page;
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unsigned long flags;
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unsigned int offset;
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spin_lock_irqsave(&pool->lock, flags);
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page = pool_find_page(pool, dma);
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if (!page) {
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spin_unlock_irqrestore(&pool->lock, flags);
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if (pool->dev)
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dev_err(pool->dev,
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"dma_pool_free %s, %p/%lx (bad dma)\n",
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pool->name, vaddr, (unsigned long)dma);
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else
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printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
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pool->name, vaddr, (unsigned long)dma);
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return;
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}
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offset = vaddr - page->vaddr;
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#ifdef DMAPOOL_DEBUG
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if ((dma - page->dma) != offset) {
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spin_unlock_irqrestore(&pool->lock, flags);
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if (pool->dev)
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dev_err(pool->dev,
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"dma_pool_free %s, %p (bad vaddr)/%Lx\n",
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pool->name, vaddr, (unsigned long long)dma);
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else
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printk(KERN_ERR
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"dma_pool_free %s, %p (bad vaddr)/%Lx\n",
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pool->name, vaddr, (unsigned long long)dma);
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return;
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}
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{
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unsigned int chain = page->offset;
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while (chain < pool->allocation) {
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if (chain != offset) {
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chain = *(int *)(page->vaddr + chain);
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continue;
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}
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spin_unlock_irqrestore(&pool->lock, flags);
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if (pool->dev)
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dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
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"already free\n", pool->name,
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(unsigned long long)dma);
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else
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printk(KERN_ERR "dma_pool_free %s, dma %Lx "
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"already free\n", pool->name,
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(unsigned long long)dma);
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return;
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}
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}
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memset(vaddr, POOL_POISON_FREED, pool->size);
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#endif
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page->in_use--;
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*(int *)vaddr = page->offset;
|
|
page->offset = offset;
|
|
/*
|
|
* Resist a temptation to do
|
|
* if (!is_page_busy(page)) pool_free_page(pool, page);
|
|
* Better have a few empty pages hang around.
|
|
*/
|
|
spin_unlock_irqrestore(&pool->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(dma_pool_free);
|
|
|
|
/*
|
|
* Managed DMA pool
|
|
*/
|
|
static void dmam_pool_release(struct device *dev, void *res)
|
|
{
|
|
struct dma_pool *pool = *(struct dma_pool **)res;
|
|
|
|
dma_pool_destroy(pool);
|
|
}
|
|
|
|
static int dmam_pool_match(struct device *dev, void *res, void *match_data)
|
|
{
|
|
return *(struct dma_pool **)res == match_data;
|
|
}
|
|
|
|
/**
|
|
* dmam_pool_create - Managed dma_pool_create()
|
|
* @name: name of pool, for diagnostics
|
|
* @dev: device that will be doing the DMA
|
|
* @size: size of the blocks in this pool.
|
|
* @align: alignment requirement for blocks; must be a power of two
|
|
* @allocation: returned blocks won't cross this boundary (or zero)
|
|
*
|
|
* Managed dma_pool_create(). DMA pool created with this function is
|
|
* automatically destroyed on driver detach.
|
|
*/
|
|
struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
|
|
size_t size, size_t align, size_t allocation)
|
|
{
|
|
struct dma_pool **ptr, *pool;
|
|
|
|
ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
|
|
if (!ptr)
|
|
return NULL;
|
|
|
|
pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
|
|
if (pool)
|
|
devres_add(dev, ptr);
|
|
else
|
|
devres_free(ptr);
|
|
|
|
return pool;
|
|
}
|
|
EXPORT_SYMBOL(dmam_pool_create);
|
|
|
|
/**
|
|
* dmam_pool_destroy - Managed dma_pool_destroy()
|
|
* @pool: dma pool that will be destroyed
|
|
*
|
|
* Managed dma_pool_destroy().
|
|
*/
|
|
void dmam_pool_destroy(struct dma_pool *pool)
|
|
{
|
|
struct device *dev = pool->dev;
|
|
|
|
WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
|
|
}
|
|
EXPORT_SYMBOL(dmam_pool_destroy);
|