Author: kib Date: Wed Sep 2 15:55:16 2020 New Revision: 365251 URL: https://svnweb.freebsd.org/changeset/base/365251
Log: Fix a page table pages leak after LA57. If the call to _pmap_allocpte() is not sleepable, it is possible that allocation of PML4 or PDP page is successful but either PDP or PD page is not. Restructured code in _pmap_allocpte() leaves zero-referenced page in the paging structure. Handle it by checking refcount of the page one level above failed alloc and free that page if its reference count is zero. Reported and tested by: pho Reviewed by: markj Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D26293 Modified: head/sys/amd64/amd64/pmap.c Modified: head/sys/amd64/amd64/pmap.c ============================================================================== --- head/sys/amd64/amd64/pmap.c Wed Sep 2 15:20:10 2020 (r365250) +++ head/sys/amd64/amd64/pmap.c Wed Sep 2 15:55:16 2020 (r365251) @@ -4101,6 +4101,21 @@ pmap_pinit(pmap_t pmap) return (pmap_pinit_type(pmap, PT_X86, pmap_flags)); } +static void +pmap_allocpte_free_unref(pmap_t pmap, vm_offset_t va, pt_entry_t *pte) +{ + vm_page_t mpg; + struct spglist free; + + mpg = PHYS_TO_VM_PAGE(*pte & PG_FRAME); + if (mpg->ref_count != 0) + return; + SLIST_INIT(&free); + _pmap_unwire_ptp(pmap, va, mpg, &free); + pmap_invalidate_page(pmap, va); + vm_page_free_pages_toq(&free, true); +} + static pml4_entry_t * pmap_allocpte_getpml4(pmap_t pmap, struct rwlock **lockp, vm_offset_t va, bool addref) @@ -4157,8 +4172,12 @@ pmap_allocpte_getpdp(pmap_t pmap, struct rwlock **lock if ((*pml4 & PG_V) == 0) { /* Have to allocate a new pdp, recurse */ if (_pmap_allocpte(pmap, pmap_pml4e_pindex(va), lockp, va) == - NULL) + NULL) { + if (pmap_is_la57(pmap)) + pmap_allocpte_free_unref(pmap, va, + pmap_pml5e(pmap, va)); return (NULL); + } allocated = true; } else { allocated = false; @@ -4332,6 +4351,8 @@ _pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex, str /* Have to allocate a new pd, recurse */ if (_pmap_allocpte(pmap, pmap_pdpe_pindex(va), lockp, va) == NULL) { + pmap_allocpte_free_unref(pmap, va, + pmap_pml4e(pmap, va)); vm_page_unwire_noq(m); vm_page_free_zero(m); return (NULL); _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
