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Date:      Wed, 16 Oct 2019 15:50:12 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r353650 - head/sys/powerpc/aim
Message-ID:  <201910161550.x9GFoCXc015809@repo.freebsd.org>

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Author: markj
Date: Wed Oct 16 15:50:12 2019
New Revision: 353650
URL: https://svnweb.freebsd.org/changeset/base/353650

Log:
  Clear PGA_WRITEABLE in moea_pvo_remove().
  
  moea_pvo_remove() might remove the last mapping of a page, in which case
  it is clearly no longer writeable.  This can happen via pmap_remove(),
  or when a CoW fault removes the last mapping of the old page.
  
  Reported and tested by:	bdragon
  Reviewed by:	alc, bdragon, kib
  MFC after:	1 week
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D22044

Modified:
  head/sys/powerpc/aim/mmu_oea.c

Modified: head/sys/powerpc/aim/mmu_oea.c
==============================================================================
--- head/sys/powerpc/aim/mmu_oea.c	Wed Oct 16 15:21:05 2019	(r353649)
+++ head/sys/powerpc/aim/mmu_oea.c	Wed Oct 16 15:50:12 2019	(r353650)
@@ -2108,23 +2108,26 @@ moea_pvo_remove(struct pvo_entry *pvo, int pteidx)
 		pvo->pvo_pmap->pm_stats.wired_count--;
 
 	/*
+	 * Remove this PVO from the PV and pmap lists.
+	 */
+	LIST_REMOVE(pvo, pvo_vlink);
+	RB_REMOVE(pvo_tree, &pvo->pvo_pmap->pmap_pvo, pvo);
+
+	/*
 	 * Save the REF/CHG bits into their cache if the page is managed.
+	 * Clear PGA_WRITEABLE if all mappings of the page have been removed.
 	 */
 	if ((pvo->pvo_vaddr & PVO_MANAGED) == PVO_MANAGED) {
-		struct	vm_page *pg;
+		struct vm_page *pg;
 
 		pg = PHYS_TO_VM_PAGE(pvo->pvo_pte.pte.pte_lo & PTE_RPGN);
 		if (pg != NULL) {
 			moea_attr_save(pg, pvo->pvo_pte.pte.pte_lo &
 			    (PTE_REF | PTE_CHG));
+			if (LIST_EMPTY(&pg->md.mdpg_pvoh))
+				vm_page_aflag_clear(pg, PGA_WRITEABLE);
 		}
 	}
-
-	/*
-	 * Remove this PVO from the PV and pmap lists.
-	 */
-	LIST_REMOVE(pvo, pvo_vlink);
-	RB_REMOVE(pvo_tree, &pvo->pvo_pmap->pmap_pvo, pvo);
 
 	/*
 	 * Remove this from the overflow list and return it to the pool



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