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Date:      Mon, 19 May 2025 03:59:12 GMT
From:      Doug Moore <dougm@FreeBSD.org>
To:        src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org
Subject:   git: 26b3641f97d9 - main - vm_page_grab_pages: avoid doomed range lookups
Message-ID:  <202505190359.54J3xCGi093692@gitrepo.freebsd.org>

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The branch main has been updated by dougm:

URL: https://cgit.FreeBSD.org/src/commit/?id=26b3641f97d9025a7c12b70935098892ae26ca0c

commit 26b3641f97d9025a7c12b70935098892ae26ca0c
Author:     Doug Moore <dougm@FreeBSD.org>
AuthorDate: 2025-05-19 03:58:00 +0000
Commit:     Doug Moore <dougm@FreeBSD.org>
CommitDate: 2025-05-19 03:58:00 +0000

    vm_page_grab_pages: avoid doomed range lookups
    
    In vm_page_grab_pages, if a range of grabbed pages has just been
    exhausted, then an immediate request for a new range is futile; we
    know there's no page there. So only try to lookup more ranges after
    allocating a page.
    
    Reviewed by:    kib, markj
    Differential Revision:  https://reviews.freebsd.org/D50394
---
 sys/vm/vm_page.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index eec85a5eb6f4..ea6fbdbc6386 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -5164,14 +5164,13 @@ vm_page_grab_pages(vm_object_t object, vm_pindex_t pindex, int allocflags,
 	i = 0;
 	vm_page_iter_init(&pages, object);
 retrylookup:
-	ahead = 0;
+	ahead = -1;
 	for (; i < count; i++) {
-		if (ahead == 0) {
+		if (ahead < 0) {
 			ahead = vm_radix_iter_lookup_range(
 			    &pages, pindex + i, &ma[i], count - i);
 		}
-		if (ahead > 0) {
-			--ahead;
+		if (ahead-- > 0) {
 			m = ma[i];
 			if (!vm_page_tryacquire(m, allocflags)) {
 				if (vm_page_grab_sleep(object, m, pindex + i,



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