From c8c5600701dec4f9c2d00c0369e1288c9a9cbe0a Mon Sep 17 00:00:00 2001 From: Justin Hibbits Date: Tue, 9 Jun 2020 21:59:13 +0000 Subject: powerpc/pmap: Fix wired memory leak in booke64 page directories Properly handle reference counts in the 64-bit pmap page directories. Otherwise all page table pages would leak due to over-referencing. This would cause a quick enter to swap on a desktop system (AmigaOne X5000) when quitting and rerunning applications, or just building world. Add an INVARIANTS check to validate no leakage at pmap release time. --- sys/powerpc/booke/pmap_64.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) (limited to 'sys') diff --git a/sys/powerpc/booke/pmap_64.c b/sys/powerpc/booke/pmap_64.c index 35e97e3f9d1b..6845baa30996 100644 --- a/sys/powerpc/booke/pmap_64.c +++ b/sys/powerpc/booke/pmap_64.c @@ -251,9 +251,7 @@ static bool unhold_free_page(pmap_t pmap, vm_page_t m) { - m->ref_count--; - if (m->ref_count == 0) { - vm_wire_sub(1); + if (vm_page_unwire_noq(m)) { vm_page_free_zero(m); return (true); } @@ -262,8 +260,8 @@ unhold_free_page(pmap_t pmap, vm_page_t m) } static vm_offset_t -alloc_or_hold_page(pmap_t pmap, vm_offset_t *ptr_tbl, uint32_t index, - bool nosleep, bool hold, bool *isnew) +get_pgtbl_page(pmap_t pmap, vm_offset_t *ptr_tbl, uint32_t index, + bool nosleep, bool hold_parent, bool *isnew) { vm_offset_t page; vm_page_t m; @@ -276,18 +274,18 @@ alloc_or_hold_page(pmap_t pmap, vm_offset_t *ptr_tbl, uint32_t index, if (ptr_tbl[index] == 0) { *isnew = true; ptr_tbl[index] = page; + if (hold_parent) { + m = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)ptr_tbl)); + m->ref_count++; + } return (page); } m = PHYS_TO_VM_PAGE(DMAP_TO_PHYS(page)); page = ptr_tbl[index]; - vm_wire_sub(1); + vm_page_unwire_noq(m); vm_page_free_zero(m); } - if (hold) { - m = PHYS_TO_VM_PAGE(pmap_kextract(page)); - m->ref_count++; - } *isnew = false; return (page); @@ -301,19 +299,18 @@ ptbl_alloc(pmap_t pmap, vm_offset_t va, bool nosleep, bool *is_new) unsigned int pdir_l1_idx = PDIR_L1_IDX(va); unsigned int pdir_idx = PDIR_IDX(va); vm_offset_t pdir_l1, pdir, ptbl; - bool hold_page; - hold_page = (pmap != kernel_pmap); - pdir_l1 = alloc_or_hold_page(pmap, (vm_offset_t *)pmap->pm_root, - pg_root_idx, nosleep, hold_page, is_new); + /* When holding a parent, no need to hold the root index pages. */ + pdir_l1 = get_pgtbl_page(pmap, (vm_offset_t *)pmap->pm_root, + pg_root_idx, nosleep, false, is_new); if (pdir_l1 == 0) return (NULL); - pdir = alloc_or_hold_page(pmap, (vm_offset_t *)pdir_l1, pdir_l1_idx, - nosleep, hold_page, is_new); + pdir = get_pgtbl_page(pmap, (vm_offset_t *)pdir_l1, pdir_l1_idx, + nosleep, !*is_new, is_new); if (pdir == 0) return (NULL); - ptbl = alloc_or_hold_page(pmap, (vm_offset_t *)pdir, pdir_idx, - nosleep, false, is_new); + ptbl = get_pgtbl_page(pmap, (vm_offset_t *)pdir, pdir_idx, + nosleep, !*is_new, is_new); return ((pte_t *)ptbl); } @@ -629,6 +626,15 @@ mmu_booke_release(pmap_t pmap) KASSERT(pmap->pm_stats.resident_count == 0, ("pmap_release: pmap resident count %ld != 0", pmap->pm_stats.resident_count)); +#ifdef INVARIANTS + /* + * Verify that all page directories are gone. + * Protects against reference count leakage. + */ + for (int i = 0; i < PG_ROOT_NENTRIES; i++) + KASSERT(pmap->pm_root[i] == 0, + ("Index %d on root page %p is non-zero!\n", i, pmap->pm_root)); +#endif uma_zfree(ptbl_root_zone, pmap->pm_root); } -- cgit v1.2.3