The branch main has been updated by alc:
URL:
https://cgit.FreeBSD.org/src/commit/?id=1a8bcf30f97e6153def2af781db2fe54f5c0d106
commit 1a8bcf30f97e6153def2af781db2fe54f5c0d106
Author: Alan Cox <a...@freebsd.org>
AuthorDate: 2021-06-30 05:59:21 +0000
Commit: Alan Cox <a...@freebsd.org>
CommitDate: 2021-06-30 18:12:25 +0000
amd64: a simplication to pmap_remove_{all,write}
Eliminate some unnecessary unlocking and relocking when we have to retry
the operation to avoid deadlock. (All of the other pmap functions that
iterate over a PV list already implemented retries without these same
unlocking and relocking operations.)
Reviewed by: kib, markj
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D30951
---
sys/amd64/amd64/pmap.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index a4046cc1f687..ea017b8a61a8 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -6307,8 +6307,8 @@ pmap_remove_all(vm_page_t m)
lock = VM_PAGE_TO_PV_LIST_LOCK(m);
pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
pa_to_pvh(VM_PAGE_TO_PHYS(m));
-retry:
rw_wlock(lock);
+retry:
while ((pv = TAILQ_FIRST(&pvh->pv_list)) != NULL) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {
@@ -6317,7 +6317,6 @@ retry:
PMAP_LOCK(pmap);
rw_wlock(lock);
if (pvh_gen != pvh->pv_gen) {
- rw_wunlock(lock);
PMAP_UNLOCK(pmap);
goto retry;
}
@@ -6336,7 +6335,6 @@ retry:
PMAP_LOCK(pmap);
rw_wlock(lock);
if (pvh_gen != pvh->pv_gen || md_gen != m->md.pv_gen) {
- rw_wunlock(lock);
PMAP_UNLOCK(pmap);
goto retry;
}
@@ -8460,8 +8458,8 @@ pmap_remove_write(vm_page_t m)
lock = VM_PAGE_TO_PV_LIST_LOCK(m);
pvh = (m->flags & PG_FICTITIOUS) != 0 ? &pv_dummy :
pa_to_pvh(VM_PAGE_TO_PHYS(m));
-retry_pv_loop:
rw_wlock(lock);
+retry_pv_loop:
TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_next, next_pv) {
pmap = PV_PMAP(pv);
if (!PMAP_TRYLOCK(pmap)) {
@@ -8471,7 +8469,6 @@ retry_pv_loop:
rw_wlock(lock);
if (pvh_gen != pvh->pv_gen) {
PMAP_UNLOCK(pmap);
- rw_wunlock(lock);
goto retry_pv_loop;
}
}
@@ -8496,7 +8493,6 @@ retry_pv_loop:
if (pvh_gen != pvh->pv_gen ||
md_gen != m->md.pv_gen) {
PMAP_UNLOCK(pmap);
- rw_wunlock(lock);
goto retry_pv_loop;
}
}
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