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Code Issues Releases Activity

Revise obj_alloc(). Most notably, use the object's lock to prevent two

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concurrent invocations from acquiring the same address(es).  Also, in case
of an incomplete allocation, free any allocated pages.

In collaboration with:	tegge
This commit is contained in:
Alan Cox 2003-08-03 06:08:48 +00:00
parent 571ecd7ab4
commit b245ac95cf
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=118380
1 changed files with 30 additions and 17 deletions
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47
sys/vm/uma_core.c
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@ -821,38 +821,51 @@ page_alloc(uma_zone_t zone, int bytes, u_int8_t *pflag, int wait)
* A pointer to the alloced memory or possibly
* NULL if M_NOWAIT is set.
*
* TODO: If we fail during a multi-page allocation release the pages that have
* already been allocated.
*/
static void *
obj_alloc(uma_zone_t zone, int bytes, u_int8_t *flags, int wait)
{
vm_offset_t zkva;
vm_offset_t retkva;
vm_object_t object;
vm_offset_t retkva, zkva;
vm_page_t p;
int pages;
int pages, startpages;
object = zone->uz_obj;
retkva = 0;
pages = zone->uz_pages;
/*
* This looks a little weird since we're getting one page at a time
*/
while (bytes > 0) {
VM_OBJECT_LOCK(zone->uz_obj);
p = vm_page_alloc(zone->uz_obj, pages,
VM_ALLOC_INTERRUPT);
VM_OBJECT_UNLOCK(zone->uz_obj);
if (p == NULL)
return (NULL);
zkva = zone->uz_kva + pages * PAGE_SIZE;
VM_OBJECT_LOCK(object);
p = TAILQ_LAST(&object->memq, pglist);
pages = p != NULL ? p->pindex + 1 : 0;
startpages = pages;
zkva = zone->uz_kva + pages * PAGE_SIZE;
for (; bytes > 0; bytes -= PAGE_SIZE) {
p = vm_page_alloc(object, pages,
VM_ALLOC_INTERRUPT | VM_ALLOC_WIRED);
if (p == NULL) {
if (pages != startpages)
pmap_qremove(retkva, pages - startpages);
while (pages != startpages) {
pages--;
p = TAILQ_LAST(&object->memq, pglist);
vm_page_lock_queues();
vm_page_unwire(p, 0);
vm_page_free(p);
vm_page_unlock_queues();
}
retkva = 0;
goto done;
}
pmap_qenter(zkva, &p, 1);
if (retkva == 0)
retkva = zkva;
pmap_qenter(zkva, &p, 1);
bytes -= PAGE_SIZE;
zkva += PAGE_SIZE;
pages += 1;
}
done:
VM_OBJECT_UNLOCK(object);
*flags = UMA_SLAB_PRIV;