Messages in this thread Patch in this message | | | From | Marek Szyprowski <> | Subject | [PATCH] arm: dma-mapping: fix potential endless loop in __dma_page_dev_to_cpu() | Date | Mon, 7 Aug 2023 17:26:57 +0200 |
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It is possible that the folio_size() of the next folio returns zero, so avoid looping with 'left' equals to zero in D-cache cleaning loop.
This fixes the following endless loop observed by RCU stall: --->8--- rcu: INFO: rcu_sched self-detected stall on CPU rcu: 0-....: (27320 ticks this GP) idle=e414/1/0x40000002 softirq=36/36 fqs=13044 rcu: (t=27385 jiffies g=-1067 q=34 ncpus=8) CPU: 0 PID: 93 Comm: kworker/0:1H Not tainted 6.5.0-rc5-next-20230807 #6981 Hardware name: Samsung Exynos (Flattened Device Tree) Workqueue: mmc_complete mmc_blk_mq_complete_work PC is at _set_bit+0x28/0x44 LR is at __dma_page_dev_to_cpu+0xdc/0x170 .. _set_bit from __dma_page_dev_to_cpu+0xdc/0x170 __dma_page_dev_to_cpu from dma_direct_unmap_sg+0x100/0x130 dma_direct_unmap_sg from dw_mci_post_req+0x68/0x6c dw_mci_post_req from mmc_blk_mq_post_req+0x34/0x100 mmc_blk_mq_post_req from mmc_blk_mq_complete_work+0x50/0x60 mmc_blk_mq_complete_work from process_one_work+0x20c/0x4d8 process_one_work from worker_thread+0x58/0x54c worker_thread from kthread+0xe0/0xfc kthread from ret_from_fork+0x14/0x2c --->8---
Fixes: cc24e9c0895c ("arm: implement the new page table range API") Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> --- arch/arm/mm/dma-mapping.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 70cb7e63a9a5..02250106e5ed 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -718,7 +718,7 @@ static void __dma_page_dev_to_cpu(struct page *page, unsigned long off, folio = folio_next(folio); } - while (left >= (ssize_t)folio_size(folio)) { + while (left && left >= (ssize_t)folio_size(folio)) { set_bit(PG_dcache_clean, &folio->flags); left -= folio_size(folio); folio = folio_next(folio); -- 2.34.1
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