From: Andrew Morton <akpm@linux-foundation.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 7/7] Remove expensive WARN_ON in pagefault_disabled_dec
Date: Wed, 15 Mar 2017 14:49:04 -0700 [thread overview]
Message-ID: <20170315144904.dcb87c7eb45aa52490d656ee@linux-foundation.org> (raw)
In-Reply-To: <20170315021431.13107-8-andi@firstfloor.org>
On Tue, 14 Mar 2017 19:14:31 -0700 Andi Kleen <andi@firstfloor.org> wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> pagefault_disabled_dec is frequently used inline, and it has a WARN_ON
> for underflow that expands to about 6.5k of extra code. The warning
> doesn't seem to be that useful and worth so much code so remove it.
>
> If it was needed could make it depending on some debug kernel option.
>
> Saves ~6.5k in my kernel
>
> text data bss dec hex filename
> 9039417 5367568 11116544 25523529 1857549 vmlinux-before-pf
> 9032805 5367568 11116544 25516917 1855b75 vmlinux-pf
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
> include/linux/uaccess.h | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> index f30c187ed785..b691aad918fb 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -12,7 +12,6 @@ static __always_inline void pagefault_disabled_inc(void)
> static __always_inline void pagefault_disabled_dec(void)
> {
> current->pagefault_disabled--;
> - WARN_ON(current->pagefault_disabled < 0);
> }
Fair enough. We could switch to VM_WARN_ON but apparently even that is now
being enabled in some production systems, which somewhat defeats its
intent...
prev parent reply other threads:[~2017-03-15 21:49 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-15 2:14 Some inline debloating, 4.11 edition Andi Kleen
2017-03-15 2:14 ` [PATCH 1/7] trace: Move trace_seq_overflowed out of line Andi Kleen
2017-03-16 0:54 ` Steven Rostedt
2017-03-16 2:27 ` Andi Kleen
2017-03-16 3:20 ` Steven Rostedt
2017-03-16 3:41 ` Steven Rostedt
2017-03-15 2:14 ` [PATCH 2/7] x86/atomic: Move __atomic_add_unless " Andi Kleen
2017-03-15 2:14 ` [PATCH 3/7] sched: Out of line __update_load_avg Andi Kleen
2017-03-15 2:14 ` [PATCH 4/7] kref: Remove WARN_ON for NULL release functions Andi Kleen
2017-03-15 2:46 ` Greg KH
2017-03-15 12:27 ` Peter Zijlstra
2017-03-15 2:14 ` [PATCH 5/7] Out of line dma_alloc/free_attrs Andi Kleen
2017-03-15 2:14 ` [PATCH 6/7] megasas: Remove expensive inline from megasas_return_cmd Andi Kleen
2017-03-15 12:17 ` Sumit Saxena
2017-03-15 2:14 ` [PATCH 7/7] Remove expensive WARN_ON in pagefault_disabled_dec Andi Kleen
2017-03-15 21:49 ` Andrew Morton [this message]
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