Re: [PATCH] swiotlb: fix the deadlock in swiotlb_do_find_slots
From: kernel test robot
Date: Mon Feb 13 2023 - 04:32:25 EST
Hi GuoRui.Yu",
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on hch-configfs/for-next v6.2-rc8]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/GuoRui-Yu/swiotlb-fix-the-deadlock-in-swiotlb_do_find_slots/20230213-143625
patch link: https://lore.kernel.org/r/20230213063604.127526-1-GuoRui.Yu%40linux.alibaba.com
patch subject: [PATCH] swiotlb: fix the deadlock in swiotlb_do_find_slots
config: x86_64-randconfig-a001-20230213 (https://download.01.org/0day-ci/archive/20230213/202302131748.pa5NGbb9-lkp@xxxxxxxxx/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/d3d8e60e47bb50892fbde7c6fa81562f8ea916a3
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review GuoRui-Yu/swiotlb-fix-the-deadlock-in-swiotlb_do_find_slots/20230213-143625
git checkout d3d8e60e47bb50892fbde7c6fa81562f8ea916a3
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/dma/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Link: https://lore.kernel.org/oe-kbuild-all/202302131748.pa5NGbb9-lkp@xxxxxxxxx/
All warnings (new ones prefixed by >>):
>> kernel/dma/swiotlb.c:668:4: warning: variable 'index_nowrap' is uninitialized when used here [-Wuninitialized]
index_nowrap += 1;
^~~~~~~~~~~~
kernel/dma/swiotlb.c:635:34: note: initialize the variable 'index_nowrap' to silence this warning
unsigned int index, index_nowrap, wrap, count = 0, i;
^
= 0
1 warning generated.
vim +/index_nowrap +668 kernel/dma/swiotlb.c
617
618 /*
619 * Find a suitable number of IO TLB entries size that will fit this request and
620 * allocate a buffer from that IO TLB pool.
621 */
622 static int swiotlb_do_find_slots(struct device *dev, int area_index,
623 phys_addr_t orig_addr, size_t alloc_size,
624 unsigned int alloc_align_mask)
625 {
626 struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
627 struct io_tlb_area *area = mem->areas + area_index;
628 unsigned long boundary_mask = dma_get_seg_boundary(dev);
629 dma_addr_t tbl_dma_addr =
630 phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
631 unsigned long max_slots = get_max_slots(boundary_mask);
632 unsigned int iotlb_align_mask =
633 dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1);
634 unsigned int nslots = nr_slots(alloc_size), stride;
635 unsigned int index, index_nowrap, wrap, count = 0, i;
636 unsigned int offset = swiotlb_align_offset(dev, orig_addr);
637 unsigned long flags;
638 unsigned int slot_base;
639 unsigned int slot_index;
640
641 BUG_ON(!nslots);
642 BUG_ON(area_index >= mem->nareas);
643
644 /*
645 * For mappings with an alignment requirement don't bother looping to
646 * unaligned slots once we found an aligned one. For allocations of
647 * PAGE_SIZE or larger only look for page aligned allocations.
648 */
649 stride = (iotlb_align_mask >> IO_TLB_SHIFT) + 1;
650 if (alloc_size >= PAGE_SIZE)
651 stride = max(stride, stride << (PAGE_SHIFT - IO_TLB_SHIFT));
652 stride = max(stride, (alloc_align_mask >> IO_TLB_SHIFT) + 1);
653
654 spin_lock_irqsave(&area->lock, flags);
655 if (unlikely(nslots > mem->area_nslabs - area->used))
656 goto not_found;
657
658 slot_base = area_index * mem->area_nslabs;
659 index = wrap = wrap_area_index(mem, ALIGN(area->index, stride));
660
661 do {
662 slot_index = slot_base + index;
663
664 if (orig_addr &&
665 (slot_addr(tbl_dma_addr, slot_index) &
666 iotlb_align_mask) != (orig_addr & iotlb_align_mask)) {
667 index = wrap_area_index(mem, index + 1);
> 668 index_nowrap += 1;
669 continue;
670 }
671
672 /*
673 * If we find a slot that indicates we have 'nslots' number of
674 * contiguous buffers, we allocate the buffers from that slot
675 * and mark the entries as '0' indicating unavailable.
676 */
677 if (!iommu_is_span_boundary(slot_index, nslots,
678 nr_slots(tbl_dma_addr),
679 max_slots)) {
680 if (mem->slots[slot_index].list >= nslots)
681 goto found;
682 }
683 index = wrap_area_index(mem, index + stride);
684 index_nowrap += stride;
685 } while (index_nowrap < wrap + mem->area_nslabs);
686
687 not_found:
688 spin_unlock_irqrestore(&area->lock, flags);
689 return -1;
690
691 found:
692 for (i = slot_index; i < slot_index + nslots; i++) {
693 mem->slots[i].list = 0;
694 mem->slots[i].alloc_size = alloc_size - (offset +
695 ((i - slot_index) << IO_TLB_SHIFT));
696 }
697 for (i = slot_index - 1;
698 io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
699 mem->slots[i].list; i--)
700 mem->slots[i].list = ++count;
701
702 /*
703 * Update the indices to avoid searching in the next round.
704 */
705 if (index + nslots < mem->area_nslabs)
706 area->index = index + nslots;
707 else
708 area->index = 0;
709 area->used += nslots;
710 spin_unlock_irqrestore(&area->lock, flags);
711 return slot_index;
712 }
713
--
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https://github.com/intel/lkp-tests