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authorHugh Dickins <hugh@veritas.com>2008-05-13 09:26:57 -0400
committerIngo Molnar <mingo@elte.hu>2008-05-13 13:36:12 -0400
commit61165d7a035f6571c7576e7f51e7230157724c8d (patch)
tree2a51d4df60fa73aa84114b7f3add4d2774177076 /arch/x86/mm/init_32.c
parent1dbd6608191cff854ab467e9880b7aeb2385ca39 (diff)
x86: fix app crashes after SMP resume
After resume on a 2cpu laptop, kernel builds collapse with a sed hang, sh or make segfault (often on 20295564), real-time signal to cc1 etc. Several hurdles to jump, but a manually-assisted bisect led to -rc1's d2bcbad5f3ad38a1c09861bca7e252dde7bb8259 x86: do not zap_low_mappings in __smp_prepare_cpus. Though the low mappings were removed at bootup, they were left behind (with Global flags helping to keep them in TLB) after resume or cpu online, causing the crashes seen. Reinstate zap_low_mappings (with local __flush_tlb_all) for each cpu_up on x86_32. This used to be serialized by smp_commenced_mask: that's now gone, but a low_mappings flag will do. No need for native_smp_cpus_done to repeat the zap: let mem_init zap BSP's low mappings just like on UP. (In passing, fix error code from native_cpu_up: do_boot_cpu returns a variety of diagnostic values, Dprintk what it says but convert to -EIO. And save_pg_dir separately before zap_low_mappings: doesn't matter now, but zapping twice in succession wiped out resume's swsusp_pg_dir.) That worked well on the duo and one quad, but wouldn't boot 3rd or 4th cpu on P4 Xeon, oopsing just after unlock_ipi_call_lock. The TLB flush IPI now being sent reveals a long-standing bug: the booting cpu has its APIC readied in smp_callin at the top of start_secondary, but isn't put into the cpu_online_map until just before that unlock_ipi_call_lock. So native_smp_call_function_mask to online cpus would send_IPI_allbutself, including the cpu just coming up, though it has been excluded from the count to wait for: by the time it handles the IPI, the call data on native_smp_call_function_mask's stack may well have been overwritten. So fall back to send_IPI_mask while cpu_online_map does not match cpu_callout_map: perhaps there's a better APICological fix to be made at the start_secondary end, but I wouldn't know that. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/init_32.c')
-rw-r--r--arch/x86/mm/init_32.c12
1 files changed, 1 insertions, 11 deletions
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index de236e419cb5..ec30d10154b6 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -438,8 +438,6 @@ void zap_low_mappings(void)
438{ 438{
439 int i; 439 int i;
440 440
441 save_pg_dir();
442
443 /* 441 /*
444 * Zap initial low-memory mappings. 442 * Zap initial low-memory mappings.
445 * 443 *
@@ -663,16 +661,8 @@ void __init mem_init(void)
663 test_wp_bit(); 661 test_wp_bit();
664 662
665 cpa_init(); 663 cpa_init();
666 664 save_pg_dir();
667 /*
668 * Subtle. SMP is doing it's boot stuff late (because it has to
669 * fork idle threads) - but it also needs low mappings for the
670 * protected-mode entry to work. We zap these entries only after
671 * the WP-bit has been tested.
672 */
673#ifndef CONFIG_SMP
674 zap_low_mappings(); 665 zap_low_mappings();
675#endif
676} 666}
677 667
678#ifdef CONFIG_MEMORY_HOTPLUG 668#ifdef CONFIG_MEMORY_HOTPLUG