From: rabin@rab.in (Rabin Vincent)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] Optimize multi-CPU tlb flushing a little more
Date: Mon, 13 Feb 2012 22:29:26 +0530 [thread overview]
Message-ID: <20120213165926.GA24426@debian> (raw)
In-Reply-To: <20120213162359.GC25655@n2100.arm.linux.org.uk>
On Mon, Feb 13, 2012 at 04:23:59PM +0000, Russell King - ARM Linux wrote:
> On Mon, Feb 13, 2012 at 09:36:35PM +0530, Rabin Vincent wrote:
> > This part conditionally calls get_cpu() but unconditionally calls
> > put_cpu():
>
> Can you try getting rid of put_cpu(), and replacing get_cpu()
> with smp_processor_id().
>
> In theory, this function should be called with preempt disabled so
> smp_processor_id() should be safe here.
Just deleting put_cpu() and replacing get_cpu() with smp_processor_id()
doesn't cause any problems on my setup, because in my setup (v7 SMP) the
test for possible_tlb_flags fails so
cpu_mask_test_cpu(smp_processor_id(),...) never gets called.
However, local_flush_tlb_mm() itself does not appear to be called with
preemption disabled, because if I reverse the check so that
smp_processor_id() is called, I get loads of the following:
BUG: using smp_processor_id() in preemptible [00000000] code: init/1
[<c0013c0c>] (unwind_backtrace+0x0/0xec) from [<c028b2a4>] (dump_stack+0x20/0x24)
[<c028b2a4>] (dump_stack+0x20/0x24) from [<c019bbb4>] (debug_smp_processor_id+0xc4/0xf8)
[<c019bbb4>] (debug_smp_processor_id+0xc4/0xf8) from [<c0012e30>] (flush_tlb_mm+0x60/0x84)
[<c0012e30>] (flush_tlb_mm+0x60/0x84) from [<c00e2578>] (setup_arg_pages+0x260/0x39c)
[<c00e2578>] (setup_arg_pages+0x260/0x39c) from [<c011ffcc>] (load_elf_binary+0x3ec/0x11d8)
[<c011ffcc>] (load_elf_binary+0x3ec/0x11d8) from [<c00e1e38>] (search_binary_handler+0xd8/0x2c8)
[<c00e1e38>] (search_binary_handler+0xd8/0x2c8) from [<c00e3b1c>] (do_execve+0x29c/0x3b4)
[<c00e3b1c>] (do_execve+0x29c/0x3b4) from [<c0011080>] (kernel_execve+0x48/0x90)
[<c0011080>] (kernel_execve+0x48/0x90) from [<c028b080>] (run_init_process+0x24/0x2c)
[<c028b080>] (run_init_process+0x24/0x2c) from [<c028b0e4>] (init_post+0x5c/0xd4)
[<c028b0e4>] (init_post+0x5c/0xd4) from [<c039bb04>] (kernel_init+0x174/0x1ac)
BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/27
[<c0013c0c>] (unwind_backtrace+0x0/0xec) from [<c028b2a4>] (dump_stack+0x20/0x24)
[<c028b2a4>] (dump_stack+0x20/0x24) from [<c019bbb4>] (debug_smp_processor_id+0xc4/0xf8)
[<c019bbb4>] (debug_smp_processor_id+0xc4/0xf8) from [<c0012e30>] (flush_tlb_mm+0x60/0x84)
[<c0012e30>] (flush_tlb_mm+0x60/0x84) from [<c00ca7e4>] (exit_mmap+0x134/0x1e8)
[<c00ca7e4>] (exit_mmap+0x134/0x1e8) from [<c001d4b0>] (mmput+0x60/0xf0)
[<c001d4b0>] (mmput+0x60/0xf0) from [<c00217bc>] (exit_mm+0x124/0x12c)
[<c00217bc>] (exit_mm+0x124/0x12c) from [<c0023084>] (do_exit+0x1e8/0x7b8)
[<c0023084>] (do_exit+0x1e8/0x7b8) from [<c0023944>] (do_group_exit+0x98/0xc4)
[<c0023944>] (do_group_exit+0x98/0xc4) from [<c0023990>] (__wake_up_parent+0x0/0x30)
[<c0023990>] (__wake_up_parent+0x0/0x30) from [<c000dca0>] (ret_fast_syscall+0x0/0x3c)
next prev parent reply other threads:[~2012-02-13 16:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-23 11:06 [PATCH] Optimize multi-CPU tlb flushing a little more Russell King - ARM Linux
2011-09-06 16:53 ` Catalin Marinas
2012-02-13 16:06 ` Rabin Vincent
2012-02-13 16:23 ` Russell King - ARM Linux
2012-02-13 16:59 ` Rabin Vincent [this message]
2012-02-14 21:59 ` Stephen Warren
2012-02-14 22:23 ` Russell King - ARM Linux
2012-02-14 22:38 ` Stephen Warren
2012-02-14 23:21 ` Stephen Warren
2012-02-14 23:34 ` Russell King - ARM Linux
2012-02-15 0:01 ` Stephen Warren
2012-02-14 18:52 ` Stephen Warren
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