Date: Wed, 8 May 2019 15:44:53 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r347346 - stable/12/sys/vm Message-ID: <201905081544.x48Firc8013377@repo.freebsd.org>
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Author: kib Date: Wed May 8 15:44:53 2019 New Revision: 347346 URL: https://svnweb.freebsd.org/changeset/base/347346 Log: MFC r346990: Fix another race between vm_map_protect() and vm_map_wire(). Modified: stable/12/sys/vm/vm_map.c Directory Properties: stable/12/ (props changed) Modified: stable/12/sys/vm/vm_map.c ============================================================================== --- stable/12/sys/vm/vm_map.c Wed May 8 15:43:22 2019 (r347345) +++ stable/12/sys/vm/vm_map.c Wed May 8 15:44:53 2019 (r347346) @@ -2347,7 +2347,7 @@ int vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, vm_prot_t new_prot, boolean_t set_max) { - vm_map_entry_t current, entry; + vm_map_entry_t current, entry, in_tran; vm_object_t obj; struct ucred *cred; vm_prot_t old_prot; @@ -2355,6 +2355,8 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_off if (start == end) return (KERN_SUCCESS); +again: + in_tran = NULL; vm_map_lock(map); /* @@ -2387,6 +2389,22 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_off vm_map_unlock(map); return (KERN_PROTECTION_FAILURE); } + if ((entry->eflags & MAP_ENTRY_IN_TRANSITION) != 0) + in_tran = entry; + } + + /* + * 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(). + */ + if (in_tran != NULL) { + in_tran->eflags |= MAP_ENTRY_NEEDS_WAKEUP; + vm_map_unlock_and_wait(map, 0); + goto again; } /*
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