[patch] linux-2.6.14-rt21 PPC32 signal delivery in realtime preemption.

From: Valentine Barshak (vbarshak_at_ru.mvista.com)
Date: 11/30/05

  • Next message: Roman Zippel: "Re: [PATCH 1/9] timer locking optimization" 
    Date:	Wed, 30 Nov 2005 17:59:23 +0300
To: lkml <linux-kernel@vger.kernel.org>

    Patch description:
    With CONFIG_PREEMPT_RT=y and CONFIG_DEBUG_PREEMPT=y
    lots of sleeping-in-invalid-context BUG messages are displayed for PPC32
    architecture.
    Kernel log:
    Freeing unused kernel memory: 108k init
    BUG: sleeping function called from invalid context init(1) at
    kernel/rt.c:1446
    in_atomic():1 [00000001], irqs_disabled():0
    Call trace:
     [c0012010] __might_sleep+0xf0/0xfc
     [c0031fd8] __spin_lock+0x38/0x70
     [c004ab68] lru_cache_add_active+0x20/0xa0
     [c0071c24] install_arg_page+0xf0/0x24c
     [c0071ee8] setup_arg_pages+0x168/0x1d4
     [c0095674] load_elf_binary+0x44c/0x11d8
     [c0072ff4] search_binary_handler+0xfc/0x338
     [c00733c0] do_execve+0x190/0x274
     [c0005b30] sys_execve+0x80/0xe0
     [c0002474] ret_from_syscall+0x0/0x70
     [c00050b8] execve+0x8/0x30
     [c00016a8] init+0x1b0/0x248
     [c0005090] original_kernel_thread+0x48/0x64

    This happens because interrupts are not enabled in the realtime preemption
    mode by the time kernel delivers signals to processes. This patch enables
    interrupts so that realtime mutexes can be acquired in the "right" context.
    The original code has been found in CONFIG_PREEMPT_RT support for i386
    architecture.
    Thanks.

    Signed-off-by: Valentine Barshak <vbarshak@ru.mvista.com>

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