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rikvanrielgregkh
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scsi: core: Use GFP_NOIO to avoid circular locking dependency
[ Upstream commit 5363ee9d110e139584c2d92a0b640bc210588506 ] Filesystems can write to disk from page reclaim with __GFP_FS set. Marc found a case where scsi_realloc_sdev_budget_map() ends up in page reclaim with GFP_KERNEL, where it could try to take filesystem locks again, leading to a deadlock. WARNING: possible circular locking dependency detected 6.13.0 #1 Not tainted ------------------------------------------------------ kswapd0/70 is trying to acquire lock: ffff8881025d5d78 (&q->q_usage_counter(io)){++++}-{0:0}, at: blk_mq_submit_bio+0x461/0x6e0 but task is already holding lock: ffffffff81ef5f40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x9f/0x760 The full lockdep splat can be found in Marc's report: https://lkml.org/lkml/2025/1/24/1101 Avoid the potential deadlock by doing the allocation with GFP_NOIO, which prevents both filesystem and block layer recursion. Reported-by: Marc Aurèle La France <tsi@tuyoix.net> Signed-off-by: Rik van Riel <riel@surriel.com> Link: https://lore.kernel.org/r/20250129104525.0ae8421e@fangorn Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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drivers/scsi/scsi_scan.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -229,7 +229,7 @@ static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
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}
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ret = sbitmap_init_node(&sdev->budget_map,
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scsi_device_max_queue_depth(sdev),
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new_shift, GFP_KERNEL,
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new_shift, GFP_NOIO,
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sdev->request_queue->node, false, true);
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if (!ret)
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sbitmap_resize(&sdev->budget_map, depth);

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