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dmarc=pass (policy=none) header.from=alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1677084801; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references; bh=frbUtv/s55VoWycBaYAQd46ZWTVXEFmJiVlXYetHK6g=; b=yMr7NYZeJucR85Ko1MVn95z6H77DLz6UTfeSvVMGjMQM7yYisBzJ18ouEqiER9nGC92bOA qqJQKp6qRAIpJ+gAdVthv4+TjOwb//SSrVQs+HMQ6x7/9IMOkTuA6rG3VSuInpIQs2wMg9 kJXdXqe06cbwmrjMS7ClBpas2FTGdzg= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045168;MF=guorui.yu@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0VcHOdvq_1677084795; Received: from localhost(mailfrom:GuoRui.Yu@linux.alibaba.com fp:SMTPD_---0VcHOdvq_1677084795) by smtp.aliyun-inc.com; Thu, 23 Feb 2023 00:53:16 +0800 From: "GuoRui.Yu" To: hch@lst.de, m.szyprowski@samsung.com Cc: robin.murphy@arm.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, GuoRui.Yu@linux.alibaba.com, linux-mm@kvack.org Subject: [PATCH v2] swiotlb: fix the deadlock in swiotlb_do_find_slots Date: Thu, 23 Feb 2023 00:53:15 +0800 Message-Id: <20230222165315.89135-1-GuoRui.Yu@linux.alibaba.com> X-Mailer: git-send-email 2.29.2.540.g3cf59784d4 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 2FF06A0017 X-Rspamd-Server: rspam01 X-Stat-Signature: hqh8o6tkepzercknezg5zyfigko4posr X-HE-Tag: 1677084800-812819 X-HE-Meta: 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 4bBzGHL4 eCuQ7XNiNdiYUMpVlHoL7CJx0beVE96ArqwwiT5Fjl+Dlpi5xsEmkOicAK+GQU8RpeFxo6osA2c8hRDfCfn2hOTFtdRANvG1KnsZ7AcDK0V8RyitV/tUlvJRpivTsicpjkys7tBjw3zqd2sUnBrF669JUpXYqaQdzAg4TM3BwM0QJy3SZu+3CBkhml4KemfYqeXWQodTWXMGQggudiU8+6Vm+MOdiXpcG/sRe6ZduX6odk8jmDiibW+zYLI6jmCjyOnemUjXinkv6UpyUuv7JpdeDng629Um3BPIegE5opmpLYoF1PGqk+4VnOQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In general, if swiotlb is sufficient, the logic of index = wrap_area_index(mem, index + 1) is fine, it will quickly take a slot and release the area->lock; But if swiotlb is insufficient and the device has min_align_mask requirements, such as NVME, we may not be able to satisfy index == wrap and exit the loop properly. In this case, other kernel threads will not be able to acquire the area->lock and release the slot, resulting in a deadlock. The current implementation of wrap_area_index does not involve a modulo operation, so adjusting the wrap to ensure the loop ends is not trivial. Introduce the index_nowrap variable to record the number of loops and exit the loop after completing the traversal. Backtraces: Other CPUs are waiting this core to exit the swiotlb_do_find_slots loop. [10199.924391] RIP: 0010:swiotlb_do_find_slots+0x1fe/0x3e0 [10199.924403] Call Trace: [10199.924404] [10199.924405] swiotlb_tbl_map_single+0xec/0x1f0 [10199.924407] swiotlb_map+0x5c/0x260 [10199.924409] ? nvme_pci_setup_prps+0x1ed/0x340 [10199.924411] dma_direct_map_page+0x12e/0x1c0 [10199.924413] nvme_map_data+0x304/0x370 [10199.924415] nvme_prep_rq.part.0+0x31/0x120 [10199.924417] nvme_queue_rq+0x77/0x1f0 ... [ 9639.596311] NMI backtrace for cpu 48 [ 9639.596336] Call Trace: [ 9639.596337] [ 9639.596338] _raw_spin_lock_irqsave+0x37/0x40 [ 9639.596341] swiotlb_do_find_slots+0xef/0x3e0 [ 9639.596344] swiotlb_tbl_map_single+0xec/0x1f0 [ 9639.596347] swiotlb_map+0x5c/0x260 [ 9639.596349] dma_direct_map_sg+0x7a/0x280 [ 9639.596352] __dma_map_sg_attrs+0x30/0x70 [ 9639.596355] dma_map_sgtable+0x1d/0x30 [ 9639.596356] nvme_map_data+0xce/0x370 ... [ 9639.595665] NMI backtrace for cpu 50 [ 9639.595682] Call Trace: [ 9639.595682] [ 9639.595683] _raw_spin_lock_irqsave+0x37/0x40 [ 9639.595686] swiotlb_release_slots.isra.0+0x86/0x180 [ 9639.595688] dma_direct_unmap_sg+0xcf/0x1a0 [ 9639.595690] nvme_unmap_data.part.0+0x43/0xc0 Fixes: 1f221a0d0dbf ("swiotlb: respect min_align_mask") Signed-off-by: GuoRui.Yu Signed-off-by: Xiaokang Hu --- kernel/dma/swiotlb.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index a34c38bbe28f..638ba3ea94f4 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -632,7 +632,7 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, unsigned int iotlb_align_mask = dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1); unsigned int nslots = nr_slots(alloc_size), stride; - unsigned int index, wrap, count = 0, i; + unsigned int index, index_nowrap = 0, wrap, count = 0, i; unsigned int offset = swiotlb_align_offset(dev, orig_addr); unsigned long flags; unsigned int slot_base; @@ -665,6 +665,7 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, (slot_addr(tbl_dma_addr, slot_index) & iotlb_align_mask) != (orig_addr & iotlb_align_mask)) { index = wrap_area_index(mem, index + 1); + index_nowrap++; continue; } @@ -680,7 +681,8 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, goto found; } index = wrap_area_index(mem, index + stride); - } while (index != wrap); + index_nowrap += stride; + } while (index_nowrap < mem->area_nslabs); not_found: spin_unlock_irqrestore(&area->lock, flags); -- 2.31.1