From: Oleg Nesterov <oleg@redhat.com>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: torvalds@linux-foundation.org, hpa@zytor.com, mingo@elte.hu,
linux-kernel@vger.kernel.org, suresh@aristanetworks.com
Subject: Re: [PATCH 1/3] coredump: flush the fpu exit state for proper multi-threaded core dump
Date: Wed, 9 May 2012 23:05:51 +0200 [thread overview]
Message-ID: <20120509210551.GB334@redhat.com> (raw)
In-Reply-To: <1336519085-27450-2-git-send-email-suresh.b.siddha@intel.com>
On 05/08, Suresh Siddha wrote:
>
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -656,6 +656,11 @@ static void exit_mm(struct task_struct * tsk)
> struct core_thread self;
> up_read(&mm->mmap_sem);
>
> + /*
> + * Flush the live extended register state to memory.
> + */
> + prepare_to_copy(tsk);
This doesn't look very nice imho, but I guess you understand this...
Perhaps we need an arch-dependent helper which saves the FPU regs
if needed.
I can be easily wrong, but I did the quick grep and I am not sure
we can rely on prepare_to_copy(). For example, it is a nop in
arch/sh/include/asm/processor_64.h. But at the same time it has
save_fpu().
OTOH, I am not sure it is safe to use prepare_to_copy() in exit_mm(),
at least in theory. God knows what it can do...
But again, I do not think I can comment this change. Perhaps this
is the right step anyway.
Oleg.
next prev parent reply other threads:[~2012-05-09 21:06 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-07 19:07 [PATCH 1/2] " Suresh Siddha
2012-05-07 19:07 ` [PATCH 2/2] x86, xsave: remove thread_has_fpu() bug check in __sanitize_i387_state() Suresh Siddha
2012-05-07 19:15 ` [PATCH 1/2] coredump: flush the fpu exit state for proper multi-threaded core dump Linus Torvalds
2012-05-07 20:09 ` Suresh Siddha
2012-05-08 23:18 ` Suresh Siddha
2012-05-08 23:18 ` [PATCH 1/3] " Suresh Siddha
2012-05-09 21:05 ` Oleg Nesterov [this message]
2012-05-09 21:32 ` Suresh Siddha
2012-05-10 16:55 ` Oleg Nesterov
2012-05-10 17:04 ` Linus Torvalds
2012-05-10 23:33 ` [PATCH v2 1/4] fork: move the real prepare_to_copy() users to arch_dup_task_struct() Suresh Siddha
2012-05-10 23:33 ` [PATCH v2 2/4] coredump: ensure the fpu state is flushed for proper multi-threaded core dump Suresh Siddha
2012-05-11 16:51 ` Oleg Nesterov
2012-05-11 19:05 ` Suresh Siddha
2012-05-13 16:11 ` Oleg Nesterov
2012-05-15 18:03 ` Suresh Siddha
2012-05-15 18:55 ` Oleg Nesterov
2012-05-17 0:17 ` [tip:x86/fpu] " tip-bot for Suresh Siddha
2012-05-10 23:33 ` [PATCH v2 3/4] x86, xsave: remove thread_has_fpu() bug check in __sanitize_i387_state() Suresh Siddha
2012-05-17 0:18 ` [tip:x86/fpu] " tip-bot for Suresh Siddha
2012-05-10 23:33 ` [PATCH v2 4/4] x86, fpu: drop the fpu state during thread exit Suresh Siddha
2012-05-17 0:19 ` [tip:x86/fpu] " tip-bot for Suresh Siddha
2012-05-11 0:17 ` [PATCH v2 1/4] fork: move the real prepare_to_copy() users to arch_dup_task_struct() Benjamin Herrenschmidt
2012-05-17 0:16 ` [tip:x86/fpu] " tip-bot for Suresh Siddha
2012-05-10 23:48 ` [PATCH 1/3] coredump: flush the fpu exit state for proper multi-threaded core dump Suresh Siddha
2012-05-08 23:18 ` [PATCH 2/3] x86, xsave: remove thread_has_fpu() bug check in __sanitize_i387_state() Suresh Siddha
2012-05-09 20:30 ` Oleg Nesterov
2012-05-09 21:18 ` Suresh Siddha
2012-05-10 16:36 ` Oleg Nesterov
2012-05-08 23:18 ` [PATCH 3/3] x86, fpu: clear the fpu state during thread exit Suresh Siddha
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