Date: Wed, 4 May 2016 17:54:14 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r299082 - head/sys/amd64/amd64 Message-ID: <201605041754.u44HsEki068735@repo.freebsd.org>
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Author: alc Date: Wed May 4 17:54:13 2016 New Revision: 299082 URL: https://svnweb.freebsd.org/changeset/base/299082 Log: Explain why pmap_copy(), pmap_enter_pde(), and pmap_enter_quick_locked() call pmap_invalidate_page() even though they are not destroying a leaf- level page table entry. Eliminate some bogus white-space characters in a comment. Reviewed by: kib Modified: head/sys/amd64/amd64/pmap.c Modified: head/sys/amd64/amd64/pmap.c ============================================================================== --- head/sys/amd64/amd64/pmap.c Wed May 4 17:52:53 2016 (r299081) +++ head/sys/amd64/amd64/pmap.c Wed May 4 17:54:13 2016 (r299082) @@ -4407,6 +4407,12 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t lockp)) { SLIST_INIT(&free); if (pmap_unwire_ptp(pmap, va, mpde, &free)) { + /* + * Although "va" is not mapped, paging- + * structure caches could nonetheless have + * entries that refer to the freed page table + * pages. Invalidate those entries. + */ pmap_invalidate_page(pmap, va); pmap_free_zero_pages(&free); } @@ -4584,6 +4590,12 @@ pmap_enter_quick_locked(pmap_t pmap, vm_ if (mpte != NULL) { SLIST_INIT(&free); if (pmap_unwire_ptp(pmap, va, mpte, &free)) { + /* + * Although "va" is not mapped, paging- + * structure caches could nonetheless have + * entries that refer to the freed page table + * pages. Invalidate those entries. + */ pmap_invalidate_page(pmap, va); pmap_free_zero_pages(&free); } @@ -4967,6 +4979,14 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pm SLIST_INIT(&free); if (pmap_unwire_ptp(dst_pmap, addr, dstmpte, &free)) { + /* + * Although "addr" is not + * mapped, paging-structure + * caches could nonetheless + * have entries that refer to + * the freed page table pages. + * Invalidate those entries. + */ pmap_invalidate_page(dst_pmap, addr); pmap_free_zero_pages(&free); @@ -5219,7 +5239,7 @@ pmap_page_is_mapped(vm_page_t m) * Destroy all managed, non-wired mappings in the given user-space * pmap. This pmap cannot be active on any processor besides the * caller. - * + * * This function cannot be applied to the kernel pmap. Moreover, it * is not intended for general use. It is only to be used during * process termination. Consequently, it can be implemented in ways
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