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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lshrdi3.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* lib/lshrdi3.c
*/
#include <linux/module.h>
#include <linux/libgcc.h>
long long notrace __lshrdi3(long long u, word_type b)
{
DWunion uu, w;
word_type bm;
if (b == 0)
return u;
uu.ll = u;
bm = 32 - b;
if (bm <= 0) {
w.s.high = 0;
w.s.low = (unsigned int) uu.s.high >> -bm;
} else {
const unsigned int carries = (unsigned int) uu.s.high << bm;
w.s.high = (unsigned int) uu.s.high >> b;
w.s.low = ((unsigned int) uu.s.low >> b) | carries;
}
return w.ll;
}
EXPORT_SYMBOL(__lshrdi3);
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