Date: Wed, 30 Jun 2021 18:15:32 GMT
From: Alan Cox <alc@FreeBSD.org>
To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org
Subject: git: 1a8bcf30f97e - main - amd64: a simplication to pmap_remove_{all, write}
Message-ID: <202106301815.15UIFWDU051025@gitrepo.freebsd.org>
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The branch main has been updated by alc: URL: https://cgit.FreeBSD.org/src/commit/?id=1a8bcf30f97e6153def2af781db2fe54f5c0d106 commit 1a8bcf30f97e6153def2af781db2fe54f5c0d106 Author: Alan Cox <alc@FreeBSD.org> AuthorDate: 2021-06-30 05:59:21 +0000 Commit: Alan Cox <alc@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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