The branch main has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=cd2105d691f446f7dbddf5965d82b9e9103bc8d2
commit cd2105d691f446f7dbddf5965d82b9e9103bc8d2 Author: Mateusz Guzik <[email protected]> AuthorDate: 2023-10-05 12:32:29 +0000 Commit: Mateusz Guzik <[email protected]> CommitDate: 2023-10-05 12:44:43 +0000 vfs cache: denote a known bug in cache_remove_cnp --- sys/kern/vfs_cache.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c index 560ff7d441c0..cc2f405d5281 100644 --- a/sys/kern/vfs_cache.c +++ b/sys/kern/vfs_cache.c @@ -1822,6 +1822,15 @@ retry_dotdot: return (1); } + /* + * XXX note that access here is completely unlocked with no provisions + * to keep the hash allocated. If one is sufficiently unlucky a + * parallel cache resize can reallocate the hash, unmap backing pages + * and cause the empty check below to fault. + * + * Fixing this has epsilon priority, but can be done with no overhead + * for this codepath with sufficient effort. + */ hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp); blp = HASH2BUCKETLOCK(hash); retry:
