Date:   Wed, 6 Dec 2017 11:02:29 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-api@...r.kernel.org, Khalid Aziz <khalid.aziz@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Andrea Arcangeli <aarcange@...hat.com>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>, linux-arch@...r.kernel.org,
        Florian Weimer <fweimer@...hat.com>,
        John Hubbard <jhubbard@...dia.com>
Subject: Re: [PATCH 1/2] mm: introduce MAP_FIXED_SAFE

On Wed 06-12-17 10:27:24, Michal Hocko wrote:
> On Wed 06-12-17 16:15:24, Michael Ellerman wrote:
[...]
> > So I think I proved above that all the arches that are using 0x80000 are
> > also using mman-common.h, and vice-versa.
> > 
> > So you can put this in mman-common.h can't your?
> 
> Yes it seems I can. I would have to double check. It is true that
> defining the new flag closer to MAP_FIXED makes some sense

OK, so some recap
those which include generic mman-common.h directly
arch/sparc/include/uapi/asm/mman.h:#include <asm-generic/mman-common.h>
arch/powerpc/include/uapi/asm/mman.h:#include <asm-generic/mman-common.h>
arch/tile/include/uapi/asm/mman.h:#include <asm-generic/mman-common.h>

then we have
arch/metag/include/asm/mman.h
which includes uapi/asm/mman.h and that is a generic one
arch/metag/include/uapi/asm/Kbuild:generic-y += mman.h

others include generic mman.h
arch/arm/include/uapi/asm/mman.h:#include <asm-generic/mman.h>
arch/frv/include/uapi/asm/mman.h:#include <asm-generic/mman.h>
arch/ia64/include/uapi/asm/mman.h:#include <asm-generic/mman.h>
arch/m32r/include/uapi/asm/mman.h:#include <asm-generic/mman.h>
arch/mn10300/include/uapi/asm/mman.h:#include <asm-generic/mman.h>
arch/score/include/uapi/asm/mman.h:#include <asm-generic/mman.h>
arch/x86/include/uapi/asm/mman.h:#include <asm-generic/mman.h>

which includes mman-common.h as well

and then we are left with
arch/alpha/include/uapi/asm/mman.h
arch/mips/include/uapi/asm/mman.h
arch/parisc/include/uapi/asm/mman.h
arch/xtensa/include/uapi/asm/mman.h

which do not include anything. So the patch can be indeed simplified.
I will fold the following into the patch. I hope nothing got left behind
but my defconfig compile test on all arches which i have a cross
compiler for succeeded.
---
commit 52a9272f419f428cb079d340f64113325516ef9b
Author: Michal Hocko <mhocko@...e.com>
Date:   Wed Dec 6 10:46:16 2017 +0100

    - define MAP_FIXED_SAFE in asm-generic/mman-common.h as per Michael
      Ellerman because all architecture which use this header can share
      the same value. This will leave us with only 4 arches which need
      special handling.

diff --git a/arch/alpha/include/uapi/asm/mman.h b/arch/alpha/include/uapi/asm/mman.h
index ef3770262925..7287dbf1e11b 100644
--- a/arch/alpha/include/uapi/asm/mman.h
+++ b/arch/alpha/include/uapi/asm/mman.h
@@ -31,7 +31,6 @@
 #define MAP_NONBLOCK	0x40000		/* do not block on IO */
 #define MAP_STACK	0x80000		/* give out an address that is best suited for process/thread stacks */
 #define MAP_HUGETLB	0x100000	/* create a huge page mapping */
-
 #define MAP_FIXED_SAFE	0x200000	/* MAP_FIXED which doesn't unmap underlying mapping */
 
 #define MS_ASYNC	1		/* sync memory asynchronously */
diff --git a/arch/powerpc/include/uapi/asm/mman.h b/arch/powerpc/include/uapi/asm/mman.h
index 3ffd284e7160..e63bc37e33af 100644
--- a/arch/powerpc/include/uapi/asm/mman.h
+++ b/arch/powerpc/include/uapi/asm/mman.h
@@ -29,6 +29,5 @@
 #define MAP_NONBLOCK	0x10000		/* do not block on IO */
 #define MAP_STACK	0x20000		/* give out an address that is best suited for process/thread stacks */
 #define MAP_HUGETLB	0x40000		/* create a huge page mapping */
-#define MAP_FIXED_SAFE	0x800000	/* MAP_FIXED which doesn't unmap underlying mapping */
 
 #endif /* _UAPI_ASM_POWERPC_MMAN_H */
diff --git a/arch/sparc/include/uapi/asm/mman.h b/arch/sparc/include/uapi/asm/mman.h
index 0c282c09fae8..d21bffd5d3dc 100644
--- a/arch/sparc/include/uapi/asm/mman.h
+++ b/arch/sparc/include/uapi/asm/mman.h
@@ -24,7 +24,5 @@
 #define MAP_NONBLOCK	0x10000		/* do not block on IO */
 #define MAP_STACK	0x20000		/* give out an address that is best suited for process/thread stacks */
 #define MAP_HUGETLB	0x40000		/* create a huge page mapping */
-#define MAP_FIXED_SAFE	0x80000		/* MAP_FIXED which doesn't unmap underlying mapping */
-
 
 #endif /* _UAPI__SPARC_MMAN_H__ */
diff --git a/arch/tile/include/uapi/asm/mman.h b/arch/tile/include/uapi/asm/mman.h
index b212f5fd5345..9b7add95926b 100644
--- a/arch/tile/include/uapi/asm/mman.h
+++ b/arch/tile/include/uapi/asm/mman.h
@@ -30,7 +30,6 @@
 #define MAP_DENYWRITE	0x0800		/* ETXTBSY */
 #define MAP_EXECUTABLE	0x1000		/* mark it as an executable */
 #define MAP_HUGETLB	0x4000		/* create a huge page mapping */
-#define MAP_FIXED_SAFE	0x8000		/* MAP_FIXED which doesn't unmap underlying mapping */
 
 
 /*
diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
index 6d319c46fd90..1eca2cb10d44 100644
--- a/include/uapi/asm-generic/mman-common.h
+++ b/include/uapi/asm-generic/mman-common.h
@@ -25,6 +25,7 @@
 #else
 # define MAP_UNINITIALIZED 0x0		/* Don't support this flag */
 #endif
+#define MAP_FIXED_SAFE	0x80000		/* MAP_FIXED which doesn't unmap underlying mapping */
 
 /*
  * Flags for mlock
diff --git a/include/uapi/asm-generic/mman.h b/include/uapi/asm-generic/mman.h
index 56cde132a80a..2dffcbf705b3 100644
--- a/include/uapi/asm-generic/mman.h
+++ b/include/uapi/asm-generic/mman.h
@@ -13,7 +13,6 @@
 #define MAP_NONBLOCK	0x10000		/* do not block on IO */
 #define MAP_STACK	0x20000		/* give out an address that is best suited for process/thread stacks */
 #define MAP_HUGETLB	0x40000		/* create a huge page mapping */
-#define MAP_FIXED_SAFE	0x80000		/* MAP_FIXED which doesn't unmap underlying mapping */
 
 /* Bits [26:31] are reserved, see mman-common.h for MAP_HUGETLB usage */
 
-- 
Michal Hocko
SUSE Labs

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