Revision 8cf66504210d308a35cca35fe9c310b1241f9fa7 authored by Qian Cai on 11 July 2019, 16:17:45 UTC, committed by Linus Torvalds on 21 July 2019, 16:57:13 UTC
The commit b3aa14f02254 ("iommu: remove the mapping_error dma_map_ops method") incorrectly changed the checking from dma_ops_alloc_iova() in map_sg() causes a crash under memory pressure as dma_ops_alloc_iova() never return DMA_MAPPING_ERROR on failure but 0, so the error handling is all wrong. kernel BUG at drivers/iommu/iova.c:801! Workqueue: kblockd blk_mq_run_work_fn RIP: 0010:iova_magazine_free_pfns+0x7d/0xc0 Call Trace: free_cpu_cached_iovas+0xbd/0x150 alloc_iova_fast+0x8c/0xba dma_ops_alloc_iova.isra.6+0x65/0xa0 map_sg+0x8c/0x2a0 scsi_dma_map+0xc6/0x160 pqi_aio_submit_io+0x1f6/0x440 [smartpqi] pqi_scsi_queue_command+0x90c/0xdd0 [smartpqi] scsi_queue_rq+0x79c/0x1200 blk_mq_dispatch_rq_list+0x4dc/0xb70 blk_mq_sched_dispatch_requests+0x249/0x310 __blk_mq_run_hw_queue+0x128/0x200 blk_mq_run_work_fn+0x27/0x30 process_one_work+0x522/0xa10 worker_thread+0x63/0x5b0 kthread+0x1d2/0x1f0 ret_from_fork+0x22/0x40 Fixes: b3aa14f02254 ("iommu: remove the mapping_error dma_map_ops method") Signed-off-by: Qian Cai <cai@lca.pw> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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memweight.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/bitmap.h>
/**
* memweight - count the total number of bits set in memory area
* @ptr: pointer to the start of the area
* @bytes: the size of the area
*/
size_t memweight(const void *ptr, size_t bytes)
{
size_t ret = 0;
size_t longs;
const unsigned char *bitmap = ptr;
for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
bytes--, bitmap++)
ret += hweight8(*bitmap);
longs = bytes / sizeof(long);
if (longs) {
BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
ret += bitmap_weight((unsigned long *)bitmap,
longs * BITS_PER_LONG);
bytes -= longs * sizeof(long);
bitmap += longs * sizeof(long);
}
/*
* The reason that this last loop is distinct from the preceding
* bitmap_weight() call is to compute 1-bits in the last region smaller
* than sizeof(long) properly on big-endian systems.
*/
for (; bytes > 0; bytes--, bitmap++)
ret += hweight8(*bitmap);
return ret;
}
EXPORT_SYMBOL(memweight);
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