mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/
synced 2026-11-08 18:57:22 +00:00
10c2b98a40
[ Upstream commit967c28b23f] After heavily stressing EROFS with several images which include a hand-crafted image of repeated patterns for more than 46 days, I found two chains could be linked with each other almost simultaneously and form a loop so that the entire loop won't be submitted. As a consequence, the corresponding file pages will remain locked forever. It can be _only_ observed on data-deduplicated compressed images. For example, consider two chains with five pclusters in total: Chain 1: 2->3->4->5 -- The tail pcluster is 5; Chain 2: 5->1->2 -- The tail pcluster is 2. Chain 2 could link to Chain 1 with pcluster 5; and Chain 1 could link to Chain 2 at the same time with pcluster 2. Since hooked chains are all linked locklessly now, I have no idea how to simply avoid the race. Instead, let's avoid hooked chains completely until I could work out a proper way to fix this and end users finally tell us that it's needed to add it back. Actually, this optimization can be found with multi-threaded workloads (especially even more often on deduplicated compressed images), yet I'm not sure about the overall system impacts of not having this compared with implementation complexity. Fixes:267f2492c8("erofs: introduce multi-reference pclusters (fully-referenced)") Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Reviewed-by: Yue Hu <huyue2@coolpad.com> Link: https://lore.kernel.org/r/20230526201459.128169-4-hsiangkao@linux.alibaba.com Signed-off-by: Sasha Levin <sashal@kernel.org>
1912 lines
48 KiB
1912 lines
48 KiB