Date: Fri, 25 May 2012 05:28:14 +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: r235973 - head/sys/amd64/amd64 Message-ID: <201205250528.q4P5SEGl082737@svn.freebsd.org>
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Author: alc Date: Fri May 25 05:28:14 2012 New Revision: 235973 URL: http://svn.freebsd.org/changeset/base/235973 Log: Correct an error in pmap_pv_reclaim(). In a rare case, when it should have returned NULL, it might instead return a pointer to a page that it had just unmapped. Modified: head/sys/amd64/amd64/pmap.c Modified: head/sys/amd64/amd64/pmap.c ============================================================================== --- head/sys/amd64/amd64/pmap.c Fri May 25 05:01:27 2012 (r235972) +++ head/sys/amd64/amd64/pmap.c Fri May 25 05:28:14 2012 (r235973) @@ -2058,14 +2058,14 @@ pmap_pv_reclaim(pmap_t locked_pmap) pt_entry_t *pte, tpte; pv_entry_t pv; vm_offset_t va; - vm_page_t free, m; + vm_page_t free, m, m_pc; uint64_t inuse, freemask; int bit, field, freed; rw_assert(&pvh_global_lock, RA_WLOCKED); PMAP_LOCK_ASSERT(locked_pmap, MA_OWNED); pmap = NULL; - free = m = NULL; + free = m_pc = NULL; TAILQ_INIT(&newtail); while ((pc = TAILQ_FIRST(&pv_chunks)) != NULL && free == NULL) { TAILQ_REMOVE(&pv_chunks, pc, pc_lru); @@ -2141,8 +2141,8 @@ pmap_pv_reclaim(pmap_t locked_pmap) PV_STAT(pc_chunk_count--); PV_STAT(pc_chunk_frees++); /* Entire chunk is free; return it. */ - m = PHYS_TO_VM_PAGE(DMAP_TO_PHYS((vm_offset_t)pc)); - dump_drop_page(m->phys_addr); + m_pc = PHYS_TO_VM_PAGE(DMAP_TO_PHYS((vm_offset_t)pc)); + dump_drop_page(m_pc->phys_addr); break; } TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list); @@ -2157,15 +2157,15 @@ pmap_pv_reclaim(pmap_t locked_pmap) if (pmap != locked_pmap) PMAP_UNLOCK(pmap); } - if (m == NULL && free != NULL) { - m = free; - free = m->right; + if (m_pc == NULL && free != NULL) { + m_pc = free; + free = m_pc->right; /* Recycle a freed page table page. */ - m->wire_count = 1; + m_pc->wire_count = 1; atomic_add_int(&cnt.v_wire_count, 1); } pmap_free_zero_pages(free); - return (m); + return (m_pc); } /*
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