svn commit: r351453 - head/sys/vm
Konstantin Belousov
kib at FreeBSD.org
Sat Aug 24 14:29:14 UTC 2019
Author: kib
Date: Sat Aug 24 14:29:13 2019
New Revision: 351453
URL: https://svnweb.freebsd.org/changeset/base/351453
Log:
Make stack grow use the same gap as stack create.
Store stack_guard_page * PAGE_SIZE into the gap->next_read field at
the time of the stack creation. This makes the used guard size
consistent between stack creation and stack grow time.
Suggested by: alc
Reviewed by: alc, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D21384
Modified:
head/sys/vm/vm_map.c
Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c Sat Aug 24 13:26:34 2019 (r351452)
+++ head/sys/vm/vm_map.c Sat Aug 24 14:29:13 2019 (r351453)
@@ -4189,8 +4189,20 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos,
rv = vm_map_insert(map, NULL, 0, gap_bot, gap_top, VM_PROT_NONE,
VM_PROT_NONE, MAP_CREATE_GUARD | (orient == MAP_STACK_GROWS_DOWN ?
MAP_CREATE_STACK_GAP_DN : MAP_CREATE_STACK_GAP_UP));
- if (rv != KERN_SUCCESS)
+ if (rv == KERN_SUCCESS) {
+ /*
+ * Gap can never successfully handle a fault, so
+ * read-ahead logic is never used for it. Re-use
+ * next_read of the gap entry to store
+ * stack_guard_page for vm_map_growstack().
+ */
+ if (orient == MAP_STACK_GROWS_DOWN)
+ new_entry->prev->next_read = sgp;
+ else
+ new_entry->next->next_read = sgp;
+ } else {
(void)vm_map_delete(map, bot, top);
+ }
return (rv);
}
@@ -4231,7 +4243,6 @@ vm_map_growstack(vm_map_t map, vm_offset_t addr, vm_ma
MPASS(!map->system_map);
- guard = stack_guard_page * PAGE_SIZE;
lmemlim = lim_cur(curthread, RLIMIT_MEMLOCK);
stacklim = lim_cur(curthread, RLIMIT_STACK);
vmemlim = lim_cur(curthread, RLIMIT_VMEM);
@@ -4258,6 +4269,7 @@ retry:
} else {
return (KERN_FAILURE);
}
+ guard = gap_entry->next_read;
max_grow = gap_entry->end - gap_entry->start;
if (guard > max_grow)
return (KERN_NO_SPACE);
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