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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2016-02-03 10:18:41 +0100 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2016-02-10 13:12:56 +0100 |
| commit | ab99a1cc7a405fed5148cf6a6fc26eec75b8a7a7 (patch) | |
| tree | e14e35351435069a1879d3868f8ea9b8c851837b /arch/s390/kvm | |
| parent | 8a08b9c7379dc881ff5f00c086877353888a982f (diff) | |
| download | linux-ab99a1cc7a405fed5148cf6a6fc26eec75b8a7a7.tar.gz linux-ab99a1cc7a405fed5148cf6a6fc26eec75b8a7a7.tar.bz2 linux-ab99a1cc7a405fed5148cf6a6fc26eec75b8a7a7.zip | |
KVM: s390: do not take mmap_sem on dirty log query
Dirty log query can take a long time for huge guests.
Holding the mmap_sem for very long times can cause some unwanted
latencies.
Turns out that we do not need to hold the mmap semaphore.
We hold the slots_lock for gfn->hva translation and walk the page
tables with that address, so no need to look at the VMAs. KVM also
holds a reference to the mm, which should prevent other things
going away. During the walk we take the necessary ptl locks.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390/kvm')
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index d0dcf73f36bc..d4bcd863b24a 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -274,7 +274,6 @@ static void kvm_s390_sync_dirty_log(struct kvm *kvm, unsigned long address; struct gmap *gmap = kvm->arch.gmap; - down_read(&gmap->mm->mmap_sem); /* Loop over all guest pages */ last_gfn = memslot->base_gfn + memslot->npages; for (cur_gfn = memslot->base_gfn; cur_gfn <= last_gfn; cur_gfn++) { @@ -283,7 +282,6 @@ static void kvm_s390_sync_dirty_log(struct kvm *kvm, if (gmap_test_and_clear_dirty(address, gmap)) mark_page_dirty(kvm, cur_gfn); } - up_read(&gmap->mm->mmap_sem); } /* Section: vm related */ |