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author | Mark Johnston <markjdb@gmail.com> | 2021-03-11 15:34:28 +0000 |
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committer | Mark Johnston <markj@FreeBSD.org> | 2021-03-14 01:09:29 +0000 |
commit | cec3990d347972c30558b135b1bc9954184fb5fe (patch) | |
tree | f17d3833b7456cedd9b66d0148a8b6e3b5c790b3 | |
parent | 8aafa7a0276302a0dcc3d0bd78b4d3842dfd1640 (diff) | |
download | src-cec3990d347972c30558b135b1bc9954184fb5fe.tar.gz src-cec3990d347972c30558b135b1bc9954184fb5fe.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.
Reviewed by: alc, kib
Reported by: gallatin
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D29203
(cherry picked from commit 968079f253c11433d47bece4b41b46fcbf985903)
-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); |