Description
In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup() A soft lockup warning was observed on a relative small system x86-64 system with 16 GB of memory when running a debug kernel with kmemleak enabled. watchdog: BUG: soft lockup - CPU#8 stuck for 33s! [kworker/8:1:134] The test system was running a workload with hot unplug happening in parallel. Then kemleak decided to disable itself due to its inability to allocate more kmemleak objects. The debug kernel has its CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE set to 40,000. The soft lockup happened in kmemleak_do_cleanup() when the existing kmemleak objects were being removed and deleted one-by-one in a loop via a workqueue. In this particular case, there are at least 40,000 objects that need to be processed and given the slowness of a debug kernel and the fact that a raw_spinlock has to be acquired and released in __delete_object(), it could take a while to properly handle all these objects. As kmemleak has been disabled in this case, the object removal and deletion process can be further optimized as locking isn't really needed. However, it is probably not worth the effort to optimize for such an edge case that should rarely happen. So the simple solution is to call cond_resched() at periodic interval in the iteration loop to avoid soft lockup.
Product status
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 9f1f4e95031f84867c5821540466d62f88dab8ca
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 1ef72a7fedc5bca70e8cc980985790de10d407aa
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before a04de4c40aab9b338dfa989cf4aec70fd187eeb2
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before f014c10d190b92aad366e56b445daffcd1c075e4
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before e21a3ddd58733ce31afcb1e5dc3cb80a4b5bc29b
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 8d2d22a55ffe35c38e69795468a7addd1a80e9ce
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 926092268efdf1ed7b55cf486356c74a9e7710d1
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 9b80430c194e4a114dc663c1025d56b4f3d0153d
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before d1534ae23c2b6be350c8ab060803fbf6e9682adc
5.4.297 (semver)
5.10.241 (semver)
5.15.190 (semver)
6.1.149 (semver)
6.6.103 (semver)
6.12.43 (semver)
6.15.11 (semver)
6.16.2 (semver)
6.17 (original_commit_for_fix)
References
git.kernel.org/...c/9f1f4e95031f84867c5821540466d62f88dab8ca
git.kernel.org/...c/1ef72a7fedc5bca70e8cc980985790de10d407aa
git.kernel.org/...c/a04de4c40aab9b338dfa989cf4aec70fd187eeb2
git.kernel.org/...c/f014c10d190b92aad366e56b445daffcd1c075e4
git.kernel.org/...c/e21a3ddd58733ce31afcb1e5dc3cb80a4b5bc29b
git.kernel.org/...c/8d2d22a55ffe35c38e69795468a7addd1a80e9ce
git.kernel.org/...c/926092268efdf1ed7b55cf486356c74a9e7710d1
git.kernel.org/...c/9b80430c194e4a114dc663c1025d56b4f3d0153d
git.kernel.org/...c/d1534ae23c2b6be350c8ab060803fbf6e9682adc
