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Remove a potential deadlock on i386 SMP by changing the lazypmap ipi and

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spin-wait code to use the same spin mutex (smp_tlb_mtx) as the TLB ipi
and spin-wait code snippets so that you can't get into the situation of
one CPU doing a TLB shootdown to another CPU that is doing a lazy pmap
shootdown each of which are waiting on each other.  With this change, only
one of the CPUs would do an IPI and spin-wait at a time.
This commit is contained in:
John Baldwin 2004-08-04 20:31:19 +00:00
parent c950c15c76
commit 0e5a07e533
2 changed files with 2 additions and 9 deletions
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10
sys/i386/i386/pmap.c
View File

@ -185,9 +185,6 @@ struct pmap kernel_pmap_store;
LIST_HEAD(pmaplist, pmap);
static struct pmaplist allpmaps;
static struct mtx allpmaps_lock;
#ifdef SMP
static struct mtx lazypmap_lock;
#endif
vm_paddr_t avail_end; /* PA of last available physical page */
vm_offset_t virtual_avail; /* VA of first avail page (after kernel bss) */
@ -333,9 +330,6 @@ pmap_bootstrap(firstaddr, loadaddr)
kernel_pmap->pm_active = -1; /* don't allow deactivation */
TAILQ_INIT(&kernel_pmap->pm_pvlist);
LIST_INIT(&allpmaps);
#ifdef SMP
mtx_init(&lazypmap_lock, "lazypmap", NULL, MTX_SPIN);
#endif
mtx_init(&allpmaps_lock, "allpmaps", NULL, MTX_SPIN);
mtx_lock_spin(&allpmaps_lock);
LIST_INSERT_HEAD(&allpmaps, kernel_pmap, pm_list);
@ -1307,7 +1301,7 @@ pmap_lazyfix(pmap_t pmap)
while ((mask = pmap->pm_active) != 0) {
spins = 50000000;
mask = mask & -mask; /* Find least significant set bit */
mtx_lock_spin(&lazypmap_lock);
mtx_lock_spin(&smp_tlb_mtx);
#ifdef PAE
lazyptd = vtophys(pmap->pm_pdpt);
#else
@ -1327,7 +1321,7 @@ pmap_lazyfix(pmap_t pmap)
break;
}
}
mtx_unlock_spin(&lazypmap_lock);
mtx_unlock_spin(&smp_tlb_mtx);
if (spins == 0)
printf("pmap_lazyfix: spun for 50000000\n");
}

1
sys/kern/subr_witness.c
View File

@ -352,7 +352,6 @@ static struct witness_order_list_entry order_lists[] = {
{ "smp rendezvous", &lock_class_mtx_spin },
#if defined(__i386__) || defined(__amd64__)
{ "tlb", &lock_class_mtx_spin },
{ "lazypmap", &lock_class_mtx_spin },
#endif
#ifdef __sparc64__
{ "ipi", &lock_class_mtx_spin },