Date: Sat, 3 Oct 2015 07:43:34 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r288556 - stable/10/sys/vm Message-ID: <201510030743.t937hY8Y072944@repo.freebsd.org>
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Author: alc Date: Sat Oct 3 07:43:33 2015 New Revision: 288556 URL: https://svnweb.freebsd.org/changeset/base/288556 Log: MFC r288281 The conversion of kmem_alloc_attr() from operating on a vm map to a vmem arena in r254025 introduced a bug in the case when an allocation is only partially successful. Specifically, the vm object lock was not being acquired before freeing the allocated pages. To address this bug, replace the existing code by a call to kmem_unback(). Change the type of a variable in kmem_alloc_attr() so that an allocation of two or more gigabytes won't fail. Replace the error handling code in kmem_back() by a call to kmem_unback(). Modified: stable/10/sys/vm/vm_kern.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/vm/vm_kern.c ============================================================================== --- stable/10/sys/vm/vm_kern.c Sat Oct 3 07:35:11 2015 (r288555) +++ stable/10/sys/vm/vm_kern.c Sat Oct 3 07:43:33 2015 (r288556) @@ -159,11 +159,10 @@ kmem_alloc_attr(vmem_t *vmem, vm_size_t vm_paddr_t high, vm_memattr_t memattr) { vm_object_t object = vmem == kmem_arena ? kmem_object : kernel_object; - vm_offset_t addr; + vm_offset_t addr, i; vm_ooffset_t offset; vm_page_t m; int pflags, tries; - int i; size = round_page(size); if (vmem_alloc(vmem, size, M_BESTFIT | flags, &addr)) @@ -184,18 +183,7 @@ retry: tries++; goto retry; } - /* - * Unmap and free the pages. - */ - if (i != 0) - pmap_remove(kernel_pmap, addr, addr + i); - while (i != 0) { - i -= PAGE_SIZE; - m = vm_page_lookup(object, - OFF_TO_IDX(offset + i)); - vm_page_unwire(m, 0); - vm_page_free(m); - } + kmem_unback(object, addr, i); vmem_free(vmem, addr, size); return (0); } @@ -353,25 +341,13 @@ retry: * aren't on any queues. */ if (m == NULL) { + VM_OBJECT_WUNLOCK(object); if ((flags & M_NOWAIT) == 0) { - VM_OBJECT_WUNLOCK(object); VM_WAIT; VM_OBJECT_WLOCK(object); goto retry; } - /* - * Unmap and free the pages. - */ - if (i != 0) - pmap_remove(kernel_pmap, addr, addr + i); - while (i != 0) { - i -= PAGE_SIZE; - m = vm_page_lookup(object, - OFF_TO_IDX(offset + i)); - vm_page_unwire(m, 0); - vm_page_free(m); - } - VM_OBJECT_WUNLOCK(object); + kmem_unback(object, addr, i); return (KERN_NO_SPACE); } if (flags & M_ZERO && (m->flags & PG_ZERO) == 0) @@ -387,6 +363,15 @@ retry: return (KERN_SUCCESS); } +/* + * kmem_unback: + * + * Unmap and free the physical pages underlying the specified virtual + * address range. + * + * A physical page must exist within the specified object at each index + * that is being unmapped. + */ void kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size) {
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