Date: Mon, 08 Dec 2025 22:33:21 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: cff67bc43df1 - main - vm_fault: only rely on PG_ZERO when the page was newly allocated Message-ID: <69375231.39dcb.1c4fcec@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=cff67bc43df14d492ccc08ec92fddceadd069953 commit cff67bc43df14d492ccc08ec92fddceadd069953 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2025-11-28 15:57:22 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2025-12-08 22:30:15 +0000 vm_fault: only rely on PG_ZERO when the page was newly allocated If the fs->m page was found invalid on the object queue, PG_ZERO flag is stale. Track the source of the page in the new fault state variable m_needs_zero, and ignore PG_ZERO if the page did not came from the allocator. Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D53963 --- sys/vm/vm_fault.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c index 3bf16778d987..f7318f96f709 100644 --- a/sys/vm/vm_fault.c +++ b/sys/vm/vm_fault.c @@ -138,6 +138,7 @@ struct faultstate { vm_object_t object; vm_pindex_t pindex; vm_page_t m; + bool m_needs_zeroing; /* Top-level map object. */ vm_object_t first_object; @@ -273,6 +274,7 @@ static void vm_fault_deallocate(struct faultstate *fs) { + fs->m_needs_zeroing = true; vm_fault_page_release(&fs->m_cow); vm_fault_page_release(&fs->m); vm_object_pip_wakeup(fs->object); @@ -1219,7 +1221,7 @@ vm_fault_zerofill(struct faultstate *fs) /* * Zero the page if necessary and mark it valid. */ - if ((fs->m->flags & PG_ZERO) == 0) { + if (fs->m_needs_zeroing) { pmap_zero_page(fs->m); } else { #ifdef INVARIANTS @@ -1352,6 +1354,7 @@ vm_fault_allocate(struct faultstate *fs, struct pctrie_iter *pages) vm_waitpfault(dset, vm_pfault_oom_wait * hz); return (FAULT_RESTART); } + fs->m_needs_zeroing = (fs->m->flags & PG_ZERO) == 0; fs->oom_started = false; return (FAULT_CONTINUE); @@ -1686,6 +1689,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, fs.fault_flags = fault_flags; fs.map = map; fs.lookup_still_valid = false; + fs.m_needs_zeroing = true; fs.oom_started = false; fs.nera = -1; fs.can_read_lock = true;
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