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The loop in vm_map_protect that verifies that all transition map

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entries are stabilized, repeatedly verifies the same entry. Check each
entry in turn.

Reviewed by: kib (code only), alc
Tested by: pho
MFC after: 7 days
Differential Revision: https://reviews.freebsd.org/D22405
This commit is contained in:
Doug Moore 2019-11-17 06:50:36 +00:00
parent 5979bb0b7d
commit bdb90e7613
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=354785
1 changed files with 7 additions and 8 deletions
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15
sys/vm/vm_map.c
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@ -2469,17 +2469,16 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end,
vm_map_unlock(map);
return (KERN_PROTECTION_FAILURE);
}
if ((entry->eflags & MAP_ENTRY_IN_TRANSITION) != 0)
in_tran = entry;
if ((current->eflags & MAP_ENTRY_IN_TRANSITION) != 0)
in_tran = current;
}
/*
* Postpone the operation until all in transition map entries
* are stabilized. In-transition entry might already have its
* pages wired and wired_count incremented, but
* MAP_ENTRY_USER_WIRED flag not yet set, and visible to other
* threads because the map lock is dropped. In this case we
* would miss our call to vm_fault_copy_entry().
* Postpone the operation until all in-transition map entries have
* stabilized. An in-transition entry might already have its pages
* wired and wired_count incremented, but not yet have its
* MAP_ENTRY_USER_WIRED flag set. In which case, we would fail to call
* vm_fault_copy_entry() in the final loop below.
*/
if (in_tran != NULL) {
in_tran->eflags |= MAP_ENTRY_NEEDS_WAKEUP;