Date: Sun, 22 Apr 2012 17:58:30 +0000 (UTC) From: Nathan Whitehorn <nwhitehorn@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r234576 - in head/sys: powerpc/aim vm Message-ID: <201204221758.q3MHwUXM050602@svn.freebsd.org>
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Author: nwhitehorn Date: Sun Apr 22 17:58:30 2012 New Revision: 234576 URL: http://svn.freebsd.org/changeset/base/234576 Log: Avoid a lock order reversal in pmap_extract_and_hold() from relocking the page. This PMAP requires an additional lock besides the PMAP lock in pmap_extract_and_hold(), which vm_page_pa_tryrelock() did not release. Suggested by: kib MFC after: 4 days Modified: head/sys/powerpc/aim/mmu_oea64.c head/sys/vm/vm_page.c Modified: head/sys/powerpc/aim/mmu_oea64.c ============================================================================== --- head/sys/powerpc/aim/mmu_oea64.c Sun Apr 22 17:14:11 2012 (r234575) +++ head/sys/powerpc/aim/mmu_oea64.c Sun Apr 22 17:58:30 2012 (r234576) @@ -1333,6 +1333,37 @@ moea64_extract(mmu_t mmu, pmap_t pm, vm_ * pmap and virtual address pair if that mapping permits the given * protection. */ + +extern int pa_tryrelock_restart; + +static int +vm_page_pa_tryrelock_moea64(pmap_t pmap, vm_paddr_t pa, vm_paddr_t *locked) +{ + /* + * This is a duplicate of vm_page_pa_tryrelock(), but with proper + * handling of the table lock + */ + vm_paddr_t lockpa; + + lockpa = *locked; + *locked = pa; + if (lockpa) { + PA_LOCK_ASSERT(lockpa, MA_OWNED); + if (PA_LOCKPTR(pa) == PA_LOCKPTR(lockpa)) + return (0); + PA_UNLOCK(lockpa); + } + if (PA_TRYLOCK(pa)) + return (0); + UNLOCK_TABLE_RD(); + PMAP_UNLOCK(pmap); + atomic_add_int(&pa_tryrelock_restart, 1); + PA_LOCK(pa); + LOCK_TABLE_RD(); + PMAP_LOCK(pmap); + return (EAGAIN); +} + vm_page_t moea64_extract_and_hold(mmu_t mmu, pmap_t pmap, vm_offset_t va, vm_prot_t prot) { @@ -1349,7 +1380,7 @@ retry: if (pvo != NULL && (pvo->pvo_pte.lpte.pte_hi & LPTE_VALID) && ((pvo->pvo_pte.lpte.pte_lo & LPTE_PP) == LPTE_RW || (prot & VM_PROT_WRITE) == 0)) { - if (vm_page_pa_tryrelock(pmap, + if (vm_page_pa_tryrelock_moea64(pmap, pvo->pvo_pte.lpte.pte_lo & LPTE_RPGN, &pa)) goto retry; m = PHYS_TO_VM_PAGE(pvo->pvo_pte.lpte.pte_lo & LPTE_RPGN); Modified: head/sys/vm/vm_page.c ============================================================================== --- head/sys/vm/vm_page.c Sun Apr 22 17:14:11 2012 (r234575) +++ head/sys/vm/vm_page.c Sun Apr 22 17:58:30 2012 (r234576) @@ -131,7 +131,7 @@ TUNABLE_INT("vm.boot_pages", &boot_pages SYSCTL_INT(_vm, OID_AUTO, boot_pages, CTLFLAG_RD, &boot_pages, 0, "number of pages allocated for bootstrapping the VM system"); -static int pa_tryrelock_restart; +int pa_tryrelock_restart; SYSCTL_INT(_vm, OID_AUTO, tryrelock_restart, CTLFLAG_RD, &pa_tryrelock_restart, 0, "Number of tryrelock restarts");
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