Date: Tue, 31 Aug 2021 19:09:49 GMT
From: Mark Johnston <markj@FreeBSD.org>
To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org
Subject: git: 605e07a27ecb - stable/13 - amd64: a simplication to pmap_remove_{all, write}
Message-ID: <202108311909.17VJ9nMJ074271@gitrepo.freebsd.org>
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The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=605e07a27ecb2e32732a0750622f9a960a982071 commit 605e07a27ecb2e32732a0750622f9a960a982071 Author: Alan Cox <alc@FreeBSD.org> AuthorDate: 2021-06-30 05:59:21 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2021-08-31 19:09:23 +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 (cherry picked from commit 1a8bcf30f97e6153def2af781db2fe54f5c0d106) --- 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 d35422924b1f..16dcddc7786a 100644 --- a/sys/amd64/amd64/pmap.c +++ b/sys/amd64/amd64/pmap.c @@ -6192,8 +6192,8 @@ 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)) { @@ -6202,7 +6202,6 @@ retry: PMAP_LOCK(pmap); rw_wlock(lock); if (pvh_gen != pvh->pv_gen) { - rw_wunlock(lock); PMAP_UNLOCK(pmap); goto retry; } @@ -6221,7 +6220,6 @@ 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; } @@ -8348,8 +8346,8 @@ 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)) { @@ -8359,7 +8357,6 @@ retry_pv_loop: rw_wlock(lock); if (pvh_gen != pvh->pv_gen) { PMAP_UNLOCK(pmap); - rw_wunlock(lock); goto retry_pv_loop; } } @@ -8384,7 +8381,6 @@ 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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