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| author | Richard Braun <rbraun@sceen.net> | 2016-09-16 04:39:02 +0200 |
|---|---|---|
| committer | Richard Braun <rbraun@sceen.net> | 2016-09-16 04:55:48 +0200 |
| commit | c78fe96446794f71a2db7d7e3d43cb15658590a3 (patch) | |
| tree | baa0dbed20f9425eca108e4062f28a82a760944c /kern/thread.h | |
| parent | ce50aa8ba8549d2cabfe9cfc9d324bd08d7430d6 (diff) | |
| download | gnumach-c78fe96446794f71a2db7d7e3d43cb15658590a3.tar.gz gnumach-c78fe96446794f71a2db7d7e3d43cb15658590a3.tar.bz2 gnumach-c78fe96446794f71a2db7d7e3d43cb15658590a3.zip | |
VM: improve pageout deadlock workaround
Commit 5dd4f67522ad0d49a2cecdb9b109251f546d4dd1 makes VM map entry
allocation done with VM privilege, so that a VM map isn't held locked
while physical allocations are paused, which may block the default
pager during page eviction, causing a system-wide deadlock.
First, it turns out that map entries aren't the only buffers allocated,
and second, their number can't be easily determined, which makes a
preallocation strategy very hard to implement.
This change generalizes the strategy of VM privilege increase when a
VM map is locked.
* device/ds_routines.c (io_done_thread): Use integer values instead
of booleans when setting VM privilege.
* kern/thread.c (thread_init, thread_wire): Likewise.
* vm/vm_pageout.c (vm_pageout): Likewise.
* kern/thread.h (struct thread): Turn member `vm_privilege' into an
unsigned integer.
* vm/vm_map.c (vm_map_lock): New function, where VM privilege is
temporarily increased.
(vm_map_unlock): New function, where VM privilege is decreased.
(_vm_map_entry_create): Remove VM privilege workaround from this
function.
* vm/vm_map.h (vm_map_lock, vm_map_unlock): Turn into functions.
Diffstat (limited to 'kern/thread.h')
| -rw-r--r-- | kern/thread.h | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kern/thread.h b/kern/thread.h index 7106fd2d..f0ed71a8 100644 --- a/kern/thread.h +++ b/kern/thread.h @@ -77,7 +77,6 @@ struct thread { struct { unsigned state:16; unsigned wake_active:1; - unsigned vm_privilege:1; unsigned active:1; }; event_t event_key; @@ -146,8 +145,8 @@ struct thread { /* VM global variables */ vm_offset_t recover; /* page fault recovery (copyin/out) */ - /* Defined above */ - /* boolean_t vm_privilege; Can use reserved memory? */ + unsigned int vm_privilege; /* Can use reserved memory? + Implemented as a counter */ /* User-visible scheduling state */ int user_stop_count; /* outstanding stops */ |