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| author | Ingo Molnar <mingo@elte.hu> | 2006-11-17 14:26:18 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-11-17 08:20:09 -0800 |
| commit | dc1829a4c378d793fb3b95d56135d89a0d7ff72a (patch) | |
| tree | 16f33c80d3f337e6eb330680342ebfceecc03b2e /arch/x86_64 | |
| parent | 0796bdb7e9e4a48b401f4fba1ee5dc79a45528ef (diff) | |
| download | linux-dc1829a4c378d793fb3b95d56135d89a0d7ff72a.tar.gz | |
[PATCH] i386/x86_64: ACPI cpu_idle_wait() fix
The scheduler on Andreas Friedrich's hyperthreading system stopped working properly: the scheduler would never move tasks to another CPU! The lask known working kernel was 2.6.8. After a couple of attempts to corner the bug, the following smoking gun was found: BIOS reported wrong ACPI idfor the processor CPU#1: set_cpus_allowed(), swapper:1, 3 -> 2 [<c0103bbe>] show_trace_log_lvl+0x34/0x4a [<c0103ceb>] show_trace+0x2c/0x2e [<c01045f8>] dump_stack+0x2b/0x2d [<c0116a77>] set_cpus_allowed+0x52/0xec [<c0101d86>] cpu_idle_wait+0x2e/0x100 [<c0259c57>] acpi_processor_power_exit+0x45/0x58 [<c0259752>] acpi_processor_remove+0x46/0xea [<c025c6fb>] acpi_start_single_object+0x47/0x54 [<c025cee5>] acpi_bus_register_driver+0xa4/0xd3 [<c04ab2d7>] acpi_processor_init+0x57/0x77 [<c01004d7>] init+0x146/0x2fd [<c0103a87>] kernel_thread_helper+0x7/0x10 a quick look at cpu_idle_wait() shows how broken that code is on i386: it changes the init task's affinity map but never restores it ... and because all userspace tasks get forked by init, they all inherited that single-CPU affinity mask. x86_64 cloned this bug too. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Andreas Friedrich <andreas.friedrich@fujitsu-siemens.com> Cc: Wolfgang Erig <Wolfgang.Erig@fujitsu-siemens.com> Cc: Andrew Morton <akpm@osdl.org> Cc: Adrian Bunk <bunk@stusta.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/x86_64')
| -rw-r--r-- | arch/x86_64/kernel/process.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index f6226055d53d..7451a4c43c16 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -144,7 +144,7 @@ static void poll_idle (void) void cpu_idle_wait(void) { unsigned int cpu, this_cpu = get_cpu(); - cpumask_t map; + cpumask_t map, tmp = current->cpus_allowed; set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); put_cpu(); @@ -167,6 +167,8 @@ void cpu_idle_wait(void) } cpus_and(map, map, cpu_online_map); } while (!cpus_empty(map)); + + set_cpus_allowed(current, tmp); } EXPORT_SYMBOL_GPL(cpu_idle_wait); |