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Correct an error in pmap_pv_reclaim(). In a rare case, when it should have

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returned NULL, it might instead return a pointer to a page that it had just
unmapped.
This commit is contained in:
Alan Cox 2012-05-25 05:28:14 +00:00
parent ae2a0aa428
commit d3d6976650
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=235973
1 changed files with 9 additions and 9 deletions
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18
sys/amd64/amd64/pmap.c
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@ -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);
}
/*