Date: Wed, 20 Nov 2013 09:03:49 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r258367 - head/sys/vm Message-ID: <201311200903.rAK93nEa019150@svn.freebsd.org>
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Author: kib Date: Wed Nov 20 09:03:48 2013 New Revision: 258367 URL: http://svnweb.freebsd.org/changeset/base/258367 Log: Vm map code performs clipping when map entry covers region which is larger than the operational region. If the op region size is zero, clipping would create a zero-sized map entry. The result is that vm map splay starts behaving inconsistently, sometimes returning zero-sized entry, sometimes the next (or previous) entry. One step further, it could result in e.g. vm_map_wire() setting MAP_ENTRY_IN_TRANSITION on the zero-sized entry, but failing to clear it in the done part. The vm_map_delete() than hangs forever waiting for the flag removal. Verify for zero-length requests and act as if it is always successfull without performing any action on the address space. Diagnosed by: pho Tested by: pho (previous version) Reviewed by: alc (previous version) Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/sys/vm/vm_map.c Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Wed Nov 20 08:47:54 2013 (r258366) +++ head/sys/vm/vm_map.c Wed Nov 20 09:03:48 2013 (r258367) @@ -1876,6 +1876,9 @@ vm_map_protect(vm_map_t map, vm_offset_t struct ucred *cred; vm_prot_t old_prot; + if (start == end) + return (KERN_SUCCESS); + vm_map_lock(map); VM_MAP_RANGE_CHECK(map, start, end); @@ -2030,12 +2033,16 @@ vm_map_madvise( case MADV_AUTOSYNC: case MADV_NOCORE: case MADV_CORE: + if (start == end) + return (KERN_SUCCESS); modify_map = 1; vm_map_lock(map); break; case MADV_WILLNEED: case MADV_DONTNEED: case MADV_FREE: + if (start == end) + return (KERN_SUCCESS); vm_map_lock_read(map); break; default: @@ -2190,6 +2197,8 @@ vm_map_inherit(vm_map_t map, vm_offset_t default: return (KERN_INVALID_ARGUMENT); } + if (start == end) + return (KERN_SUCCESS); vm_map_lock(map); VM_MAP_RANGE_CHECK(map, start, end); if (vm_map_lookup_entry(map, start, &temp_entry)) { @@ -2222,6 +2231,8 @@ vm_map_unwire(vm_map_t map, vm_offset_t int rv; boolean_t need_wakeup, result, user_unwire; + if (start == end) + return (KERN_SUCCESS); user_unwire = (flags & VM_MAP_WIRE_USER) ? TRUE : FALSE; vm_map_lock(map); VM_MAP_RANGE_CHECK(map, start, end); @@ -2392,6 +2403,8 @@ vm_map_wire(vm_map_t map, vm_offset_t st boolean_t fictitious, need_wakeup, result, user_wire; vm_prot_t prot; + if (start == end) + return (KERN_SUCCESS); prot = 0; if (flags & VM_MAP_WIRE_WRITE) prot |= VM_PROT_WRITE; @@ -2833,6 +2846,8 @@ vm_map_delete(vm_map_t map, vm_offset_t vm_map_entry_t first_entry; VM_MAP_ASSERT_LOCKED(map); + if (start == end) + return (KERN_SUCCESS); /* * Find the start of the region, and clip it
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