mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-06 10:58:48 +09:00
d3b39ea248
[ 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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.