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| author | Mark Johnston <markjdb@gmail.com> | 2021-03-14 16:39:23 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2021-03-14 16:39:23 +0000 |
| commit | 45910f663893fab38eaf95c70aaeff75035334c1 (patch) | |
| tree | 492048d7d716c99f80930c439b3b592a58d03804 | |
| parent | e6e8762dff593cbd1da4cc5a3b8f75b183c23837 (diff) | |
| download | src-45910f663893fab38eaf95c70aaeff75035334c1.tar.gz src-45910f663893fab38eaf95c70aaeff75035334c1.zip | |
vm_reserv: Fix list locking in vm_reserv_reclaim_contig()
The per-domain partpop queue is locked by the combination of the
per-domain lock and individual reservation mutexes.
vm_reserv_reclaim_contig() scans the queue looking for partially
populated reservations that can be reclaimed in order to satisfy the
caller's allocation.
During the scan, we drop the per-domain lock. At this point, the rvn
pointer may be invalidated. Take care to load rvn after re-acquiring
the per-domain lock.
While here, simplify the condition used to check whether a reservation
was dequeued while the per-domain lock was dropped.
Approved by: re (gjb)
Reviewed by: alc, kib
Reported by: gallatin
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D29203
(cherry picked from commit 968079f253c11433d47bece4b41b46fcbf985903)
(cherry picked from commit cec3990d347972c30558b135b1bc9954184fb5fe)
| -rw-r--r-- | sys/vm/vm_reserv.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/sys/vm/vm_reserv.c b/sys/vm/vm_reserv.c index e7f542a66fdb..a9602c3977df 100644 --- a/sys/vm/vm_reserv.c +++ b/sys/vm/vm_reserv.c @@ -1344,8 +1344,8 @@ vm_reserv_reclaim_contig(int domain, u_long npages, vm_paddr_t low, TAILQ_INSERT_AFTER(queue, rv, marker, partpopq); vm_reserv_domain_unlock(domain); vm_reserv_lock(rv); - if (!rv->inpartpopq || - TAILQ_NEXT(rv, partpopq) != marker) { + if (TAILQ_PREV(marker, vm_reserv_queue, partpopq) != + rv) { vm_reserv_unlock(rv); vm_reserv_domain_lock(domain); rvn = TAILQ_NEXT(marker, partpopq); @@ -1363,8 +1363,9 @@ vm_reserv_reclaim_contig(int domain, u_long npages, vm_paddr_t low, vm_reserv_unlock(rv); return (true); } - vm_reserv_unlock(rv); vm_reserv_domain_lock(domain); + rvn = TAILQ_NEXT(rv, partpopq); + vm_reserv_unlock(rv); } vm_reserv_domain_unlock(domain); vm_reserv_domain_scan_unlock(domain); |