On Tue, Jan 25, 2022 at 07:54:52AM +0000, Klemens Nanni wrote: > > Could we use a vm_map_assert_locked() or something similar that reflect > > the exclusive or shared (read) lock comments? I don't trust comments. > > It's too easy to miss a lock in a code path. > > This survives desktop usage, running regress and building kernels on > amd64. > > I'll throw it at sparc64 soon. > > > > > > So annotate functions using `size' wrt. the required lock.
Here's a better diff that asserts for read, write or any type of vm_map lock. vm_map_lock() and vm_map_lock_read() are used for exclusive and shared access respectively; unless I missed something, no code path is purely protected by vm_map_lock_read() alone, i.e. functions called with a read lock held by the callee are also called with a write lock elsewhere. That means my new vm_map_assert_locked_read() is currently unused, but vm_map_assert_locked_any() and vm_map_assert_locked_write() are now used to validate existing function comments as well as a few new places. amd64 and sparc64 are happy with this, both daily drivers as well as build/regress machines. I'd appreciate more tests and reports about running with this diff and mmap(2) unlocked. Index: uvm_map.c =================================================================== RCS file: /cvs/src/sys/uvm/uvm_map.c,v retrieving revision 1.282 diff -u -p -r1.282 uvm_map.c --- uvm_map.c 21 Dec 2021 22:21:32 -0000 1.282 +++ uvm_map.c 27 Jan 2022 10:45:47 -0000 @@ -805,6 +805,8 @@ uvm_map_sel_limits(vaddr_t *min, vaddr_t * Fills in *start_ptr and *end_ptr to be the first and last entry describing * the space. * If called with prefilled *start_ptr and *end_ptr, they are to be correct. + * + * map must be at least read-locked. */ int uvm_map_isavail(struct vm_map *map, struct uvm_addr_state *uaddr, @@ -815,6 +817,8 @@ uvm_map_isavail(struct vm_map *map, stru struct uvm_map_addr *atree; struct vm_map_entry *i, *i_end; + vm_map_assert_locked_any(map); + if (addr + sz < addr) return 0; @@ -1821,6 +1825,8 @@ boolean_t uvm_map_lookup_entry(struct vm_map *map, vaddr_t address, struct vm_map_entry **entry) { + vm_map_assert_locked_any(map); + *entry = uvm_map_entrybyaddr(&map->addr, address); return *entry != NULL && !UVM_ET_ISHOLE(*entry) && (*entry)->start <= address && (*entry)->end > address; @@ -2206,6 +2212,8 @@ uvm_unmap_kill_entry(struct vm_map *map, * If remove_holes, then remove ET_HOLE entries as well. * If markfree, entry will be properly marked free, otherwise, no replacement * entry will be put in the tree (corrupting the tree). + * + * map must be locked. */ void uvm_unmap_remove(struct vm_map *map, vaddr_t start, vaddr_t end, @@ -2214,6 +2222,8 @@ uvm_unmap_remove(struct vm_map *map, vad { struct vm_map_entry *prev_hint, *next, *entry; + vm_map_assert_locked_write(map); + start = MAX(start, map->min_offset); end = MIN(end, map->max_offset); if (start >= end) @@ -2976,12 +2986,17 @@ uvm_tree_sanity(struct vm_map *map, char UVM_ASSERT(map, addr == vm_map_max(map), file, line); } +/* + * map must be at least read-locked. + */ void uvm_tree_size_chk(struct vm_map *map, char *file, int line) { struct vm_map_entry *iter; vsize_t size; + vm_map_assert_locked_any(map); + size = 0; RBT_FOREACH(iter, uvm_map_addr, &map->addr) { if (!UVM_ET_ISHOLE(iter)) @@ -4268,7 +4283,7 @@ uvm_map_submap(struct vm_map *map, vaddr * uvm_map_checkprot: check protection in map * * => must allow specific protection in a fully allocated region. - * => map mut be read or write locked by caller. + * => map must be read or write locked by caller. */ boolean_t uvm_map_checkprot(struct vm_map *map, vaddr_t start, vaddr_t end, @@ -4276,6 +4291,8 @@ uvm_map_checkprot(struct vm_map *map, va { struct vm_map_entry *entry; + vm_map_assert_locked_any(map); + if (start < map->min_offset || end > map->max_offset || start > end) return FALSE; if (start == end) @@ -5557,6 +5577,46 @@ vm_map_unbusy_ln(struct vm_map *map, cha mtx_leave(&map->flags_lock); if (oflags & VM_MAP_WANTLOCK) wakeup(&map->flags); +} + +void +vm_map_assert_locked_any_ln(struct vm_map *map, char *file, int line) +{ + LPRINTF(("map assert read or write locked: %p (at %s %d)\n", map, file, line)); + if ((map->flags & VM_MAP_INTRSAFE) == 0) + rw_assert_anylock(&map->lock); + else + MUTEX_ASSERT_LOCKED(&map->mtx); +} + +void +vm_map_assert_locked_read_ln(struct vm_map *map, char *file, int line) +{ + LPRINTF(("map assert read locked: %p (at %s %d)\n", map, file, line)); + if ((map->flags & VM_MAP_INTRSAFE) == 0) + rw_assert_rdlock(&map->lock); + else + MUTEX_ASSERT_LOCKED(&map->mtx); +} + +void +vm_map_assert_locked_write_ln(struct vm_map *map, char *file, int line) +{ + LPRINTF(("map assert write locked: %p (at %s %d)\n", map, file, line)); + if ((map->flags & VM_MAP_INTRSAFE) == 0) + rw_assert_wrlock(&map->lock); + else + MUTEX_ASSERT_LOCKED(&map->mtx); +} + +void +vm_map_assert_unlocked_ln(struct vm_map *map, char *file, int line) +{ + LPRINTF(("map assert unlocked: %p (at %s %d)\n", map, file, line)); + if ((map->flags & VM_MAP_INTRSAFE) == 0) + rw_assert_unlocked(&map->lock); + else + MUTEX_ASSERT_UNLOCKED(&map->mtx); } #ifndef SMALL_KERNEL Index: uvm_map.h =================================================================== RCS file: /cvs/src/sys/uvm/uvm_map.h,v retrieving revision 1.71 diff -u -p -r1.71 uvm_map.h --- uvm_map.h 15 Dec 2021 12:53:53 -0000 1.71 +++ uvm_map.h 27 Jan 2022 10:19:56 -0000 @@ -262,6 +262,7 @@ RBT_PROTOTYPE(uvm_map_addr, vm_map_entry * a atomic operations * I immutable after creation or exec(2) * v `vm_map_lock' (this map `lock' or `mtx') + * f `flags_lock' */ struct vm_map { struct pmap *pmap; /* [I] Physical map */ @@ -272,9 +273,9 @@ struct vm_map { struct uvm_map_addr addr; /* [v] Entry tree, by addr */ - vsize_t size; /* virtual size */ + vsize_t size; /* [v] virtual size */ int ref_count; /* [a] Reference count */ - int flags; /* flags */ + int flags; /* [f] flags */ struct mutex flags_lock; /* flags lock */ unsigned int timestamp; /* Version number */ @@ -419,6 +420,10 @@ void vm_map_downgrade_ln(struct vm_map* void vm_map_upgrade_ln(struct vm_map*, char*, int); void vm_map_busy_ln(struct vm_map*, char*, int); void vm_map_unbusy_ln(struct vm_map*, char*, int); +void vm_map_assert_locked_any_ln(struct vm_map*, char*, int); +void vm_map_assert_locked_read_ln(struct vm_map*, char*, int); +void vm_map_assert_locked_write_ln(struct vm_map*, char*, int); +void vm_map_assert_unlocked_ln(struct vm_map*, char*, int); #ifdef DIAGNOSTIC #define vm_map_lock_try(map) vm_map_lock_try_ln(map, __FILE__, __LINE__) @@ -430,6 +435,10 @@ void vm_map_unbusy_ln(struct vm_map*, c #define vm_map_upgrade(map) vm_map_upgrade_ln(map, __FILE__, __LINE__) #define vm_map_busy(map) vm_map_busy_ln(map, __FILE__, __LINE__) #define vm_map_unbusy(map) vm_map_unbusy_ln(map, __FILE__, __LINE__) +#define vm_map_assert_locked_any(map) vm_map_assert_locked_any_ln(map, __FILE__, __LINE__) +#define vm_map_assert_locked_read(map) vm_map_assert_locked_read_ln(map, __FILE__, __LINE__) +#define vm_map_assert_locked_write(map) vm_map_assert_locked_write_ln(map, __FILE__, __LINE__) +#define vm_map_assert_unlocked(map) vm_map_assert_unlocked_ln(map, __FILE__, __LINE__) #else #define vm_map_lock_try(map) vm_map_lock_try_ln(map, NULL, 0) #define vm_map_lock(map) vm_map_lock_ln(map, NULL, 0) @@ -440,6 +449,10 @@ void vm_map_unbusy_ln(struct vm_map*, c #define vm_map_upgrade(map) vm_map_upgrade_ln(map, NULL, 0) #define vm_map_busy(map) vm_map_busy_ln(map, NULL, 0) #define vm_map_unbusy(map) vm_map_unbusy_ln(map, NULL, 0) +#define vm_map_assert_locked_any(map) vm_map_assert_locked_any_ln(map, NULL, 0) +#define vm_map_assert_locked_read(map) vm_map_assert_locked_read_ln(map, NULL, 0) +#define vm_map_assert_locked_write(map) vm_map_assert_locked_write_ln(map, NULL, 0) +#define vm_map_assert_unlocked(map) vm_map_assert_unlocked_ln(map, NULL, 0) #endif void uvm_map_lock_entry(struct vm_map_entry *); Index: uvm_fault.c =================================================================== RCS file: /cvs/src/sys/uvm/uvm_fault.c,v retrieving revision 1.124 diff -u -p -r1.124 uvm_fault.c --- uvm_fault.c 28 Dec 2021 13:16:28 -0000 1.124 +++ uvm_fault.c 26 Jan 2022 16:23:42 -0000 @@ -1602,6 +1602,7 @@ uvm_fault_unwire_locked(vm_map_t map, va struct vm_page *pg; KASSERT((map->flags & VM_MAP_INTRSAFE) == 0); + vm_map_assert_locked_any(map); /* * we assume that the area we are unwiring has actually been wired