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From: Andi Kleen <andi@firstfloor.org>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>
Subject: [PATCH 7/7] Remove expensive WARN_ON in pagefault_disabled_dec
Date: Tue, 14 Mar 2017 19:14:31 -0700
Message-ID: <20170315021431.13107-8-andi@firstfloor.org> (raw)
In-Reply-To: <20170315021431.13107-1-andi@firstfloor.org>

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);
 }
 
 /*
-- 
2.9.3

  parent reply index

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 ` Andi Kleen [this message]
2017-03-15 21:49   ` [PATCH 7/7] Remove expensive WARN_ON in pagefault_disabled_dec Andrew Morton

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