[PATCH V3 0/3] Refine numa_emulation

[PATCH V3 0/3] Refine numa_emulation

[Wei Yang]

My previous patch "x86/mm/numa: Remove numa_nodemask_from_meminfo()" hits a
problem in numa_emulation. The reason is numa_nodes_parsed is not set
correctly after emulation.

This patch set tries to fix this and also with two code refine.

Detailed discussions are in this thread:

    https://lkml.org/lkml/2017/3/13/1230

and test result is posted :

    https://lkml.org/lkml/2017/4/10/641

V3:
    * remote the error branch and split the loop into a function
    * refine the comment

V2:
    * refresh the change log based on David comments
    * use nodes_clear()

Wei Yang (3):
  x86/numa_emulation: refine the calculation of max_emu_nid and
    dfl_phys_nid
  x86/numa_emulation: assign physnode_mask directly from
    numa_nodes_parsed
  x86/numa_emulation: restructures numa_nodes_parsed from emulated nodes

 arch/x86/mm/numa_emulation.c | 55 ++++++++++++++++++++++++++------------------
 1 file changed, 32 insertions(+), 23 deletions(-)

-- 
2.11.0

[PATCH V3 1/3] x86/numa_emulation: refine the calculation of max_emu_nid and dfl_phys_nid

[Wei Yang]

max_emu_nid and dfl_phys_nid is calculated from emu_nid_to_phys[], which is
calculated in split_nodes_xxx_interleave(). From the logic in these
functions, it is assured the emu_nid_to_phys[] has meaningful value if it
return successfully and ensures dfl_phys_nid will get a valid value.

This patch removes the error branch to check invalid dfl_phys_nid and
abstract this part to a function for readability.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 arch/x86/mm/numa_emulation.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index a8f90ce3dedf..a6d55308660f 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -280,6 +280,22 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 	return 0;
 }
 
+int __init setup_emu2phys_nid(int *dfl_phys_nid)
+{
+	int i, max_emu_nid = 0;
+
+	*dfl_phys_nid = NUMA_NO_NODE;
+	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
+		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
+			max_emu_nid = i;
+			if (*dfl_phys_nid == NUMA_NO_NODE)
+				*dfl_phys_nid = emu_nid_to_phys[i];
+		}
+	}
+
+	return max_emu_nid;
+}
+
 /**
  * numa_emulation - Emulate NUMA nodes
  * @numa_meminfo: NUMA configuration to massage
@@ -376,19 +392,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 	 * Determine the max emulated nid and the default phys nid to use
 	 * for unmapped nodes.
 	 */
-	max_emu_nid = 0;
-	dfl_phys_nid = NUMA_NO_NODE;
-	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
-		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
-			max_emu_nid = i;
-			if (dfl_phys_nid == NUMA_NO_NODE)
-				dfl_phys_nid = emu_nid_to_phys[i];
-		}
-	}
-	if (dfl_phys_nid == NUMA_NO_NODE) {
-		pr_warning("NUMA: Warning: can't determine default physical node, disabling emulation\n");
-		goto no_emu;
-	}
+	max_emu_nid = setup_emu2phys_nid(&dfl_phys_nid);
 
 	/* commit */
 	*numa_meminfo = ei;
-- 
2.11.0

[tip:x86/debug] x86/numa_emulation: Refine the calculation of max_emu_nid and dfl_phys_nid

[tip-bot for Wei Yang]

Commit-ID:  158f424f427e686816bc64cd623e3bfc3390dfb0
Gitweb:     http://git.kernel.org/tip/158f424f427e686816bc64cd623e3bfc3390dfb0
Author:     Wei Yang <richard.weiyang@gmail.com>
AuthorDate: Sat, 8 Jul 2017 09:30:57 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 18 Jul 2017 11:16:49 +0200

x86/numa_emulation: Refine the calculation of max_emu_nid and dfl_phys_nid

max_emu_nid and dfl_phys_nid is calculated from emu_nid_to_phys[], which is
calculated in split_nodes_xxx_interleave(). From the logic in these
functions, it is assured the emu_nid_to_phys[] has meaningful value if it
return successfully and ensures dfl_phys_nid will get a valid value.

This patch removes the error branch to check invalid dfl_phys_nid and
abstracts out this part to a function for readability.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bp@alien8.de
Cc: kirill@shutemov.name
Cc: rientjes@google.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20170708013059.29708-2-richard.weiyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/numa_emulation.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index a8f90ce..a6d5530 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -280,6 +280,22 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 	return 0;
 }
 
+int __init setup_emu2phys_nid(int *dfl_phys_nid)
+{
+	int i, max_emu_nid = 0;
+
+	*dfl_phys_nid = NUMA_NO_NODE;
+	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
+		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
+			max_emu_nid = i;
+			if (*dfl_phys_nid == NUMA_NO_NODE)
+				*dfl_phys_nid = emu_nid_to_phys[i];
+		}
+	}
+
+	return max_emu_nid;
+}
+
 /**
  * numa_emulation - Emulate NUMA nodes
  * @numa_meminfo: NUMA configuration to massage
@@ -376,19 +392,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 	 * Determine the max emulated nid and the default phys nid to use
 	 * for unmapped nodes.
 	 */
-	max_emu_nid = 0;
-	dfl_phys_nid = NUMA_NO_NODE;
-	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
-		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
-			max_emu_nid = i;
-			if (dfl_phys_nid == NUMA_NO_NODE)
-				dfl_phys_nid = emu_nid_to_phys[i];
-		}
-	}
-	if (dfl_phys_nid == NUMA_NO_NODE) {
-		pr_warning("NUMA: Warning: can't determine default physical node, disabling emulation\n");
-		goto no_emu;
-	}
+	max_emu_nid = setup_emu2phys_nid(&dfl_phys_nid);
 
 	/* commit */
 	*numa_meminfo = ei;

Re: [PATCH V3 1/3] x86/numa_emulation: refine the calculation of max_emu_nid and dfl_phys_nid

[Borislav Petkov]

On Sat, Jul 08, 2017 at 09:30:57AM +0800, Wei Yang wrote:
> max_emu_nid and dfl_phys_nid is calculated from emu_nid_to_phys[], which is
> calculated in split_nodes_xxx_interleave(). From the logic in these

$ git grep split_nodes_xxx_interleave
$

> functions, it is assured the emu_nid_to_phys[] has meaningful value if it
> return successfully and ensures dfl_phys_nid will get a valid value.
> 
> This patch removes the error branch to check invalid dfl_phys_nid and

So the check doesn't hurt anyone.

On the contrary - it is an "assertion" of sorts in otherwise complex
code and actually documents the fact that by then emu_nid_to_phys[]
needs to be setup properly.

And it is especially useful if someone decides to change that code in
the future, for whatever reason, and gets to hit that check - it'll even
be helpful in that case.

So I'd vote for keeping that check and not doing anything.

While we're at it, never say "this patch" in a commit message - that is
tautologically obvious.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--

Re: [PATCH V3 1/3] x86/numa_emulation: refine the calculation of max_emu_nid and dfl_phys_nid

[Wei Yang]

[-- Attachment #1: Type: text/plain, Size: 1317 bytes --]

On Tue, Jul 18, 2017 at 01:03:39PM +0200, Borislav Petkov wrote:
>On Sat, Jul 08, 2017 at 09:30:57AM +0800, Wei Yang wrote:
>> max_emu_nid and dfl_phys_nid is calculated from emu_nid_to_phys[], which is
>> calculated in split_nodes_xxx_interleave(). From the logic in these
>
>$ git grep split_nodes_xxx_interleave
>$
>
>> functions, it is assured the emu_nid_to_phys[] has meaningful value if it
>> return successfully and ensures dfl_phys_nid will get a valid value.
>> 
>> This patch removes the error branch to check invalid dfl_phys_nid and
>
>So the check doesn't hurt anyone.
>
>On the contrary - it is an "assertion" of sorts in otherwise complex
>code and actually documents the fact that by then emu_nid_to_phys[]
>needs to be setup properly.
>
>And it is especially useful if someone decides to change that code in
>the future, for whatever reason, and gets to hit that check - it'll even
>be helpful in that case.
>
>So I'd vote for keeping that check and not doing anything.
>
>While we're at it, never say "this patch" in a commit message - that is
>tautologically obvious.
>

Hi, Borislav 

Thanks for your comment, I will this in my mind.

>-- 
>Regards/Gruss,
>    Boris.
>
>ECO tip #101: Trim your mails when you reply.
>--

-- 
Wei Yang
Help you, Help me

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

[PATCH V3 2/3] x86/numa_emulation: assign physnode_mask directly from numa_nodes_parsed

[Wei Yang]

numa_init() has already called init_func(), which is responsible for
setting numa_nodes_parsed, so use this nodemask instead of re-finding it
when calling numa_emulation().

This patch gets the physnode_mask directly from numa_nodes_parsed. At
the same time, it corrects the comment of these two functions.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/mm/numa_emulation.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index a6d55308660f..80904ede2e7f 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -75,13 +75,15 @@ static int __init emu_setup_memblk(struct numa_meminfo *ei,
 
 /*
  * Sets up nr_nodes fake nodes interleaved over physical nodes ranging from addr
- * to max_addr.  The return value is the number of nodes allocated.
+ * to max_addr.
+ *
+ * Returns zero on success or negative on error.
  */
 static int __init split_nodes_interleave(struct numa_meminfo *ei,
 					 struct numa_meminfo *pi,
 					 u64 addr, u64 max_addr, int nr_nodes)
 {
-	nodemask_t physnode_mask = NODE_MASK_NONE;
+	nodemask_t physnode_mask = numa_nodes_parsed;
 	u64 size;
 	int big;
 	int nid = 0;
@@ -116,9 +118,6 @@ static int __init split_nodes_interleave(struct numa_meminfo *ei,
 		return -1;
 	}
 
-	for (i = 0; i < pi->nr_blks; i++)
-		node_set(pi->blk[i].nid, physnode_mask);
-
 	/*
 	 * Continue to fill physical nodes with fake nodes until there is no
 	 * memory left on any of them.
@@ -200,13 +199,15 @@ static u64 __init find_end_of_node(u64 start, u64 max_addr, u64 size)
 
 /*
  * Sets up fake nodes of `size' interleaved over physical nodes ranging from
- * `addr' to `max_addr'.  The return value is the number of nodes allocated.
+ * `addr' to `max_addr'.
+ *
+ * Returns zero on success or negative on error.
  */
 static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 					      struct numa_meminfo *pi,
 					      u64 addr, u64 max_addr, u64 size)
 {
-	nodemask_t physnode_mask = NODE_MASK_NONE;
+	nodemask_t physnode_mask = numa_nodes_parsed;
 	u64 min_size;
 	int nid = 0;
 	int i, ret;
@@ -231,9 +232,6 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 	}
 	size &= FAKE_NODE_MIN_HASH_MASK;
 
-	for (i = 0; i < pi->nr_blks; i++)
-		node_set(pi->blk[i].nid, physnode_mask);
-
 	/*
 	 * Fill physical nodes with fake nodes of size until there is no memory
 	 * left on any of them.
-- 
2.11.0

[tip:x86/debug] x86/numa_emulation: Assign physnode_mask directly from numa_nodes_parsed

[tip-bot for Wei Yang]

Commit-ID:  d80a9eb3c78d7d0c823a8224cd6e3b37ebdfd8cd
Gitweb:     http://git.kernel.org/tip/d80a9eb3c78d7d0c823a8224cd6e3b37ebdfd8cd
Author:     Wei Yang <richard.weiyang@gmail.com>
AuthorDate: Sat, 8 Jul 2017 09:30:58 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 18 Jul 2017 11:16:49 +0200

x86/numa_emulation: Assign physnode_mask directly from numa_nodes_parsed

numa_init() has already called init_func(), which is responsible for
setting numa_nodes_parsed, so use this nodemask instead of re-finding it
when calling numa_emulation().

This patch gets the physnode_mask directly from numa_nodes_parsed. At
the same time, it corrects the comment of these two functions.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bp@alien8.de
Cc: kirill@shutemov.name
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20170708013059.29708-3-richard.weiyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/numa_emulation.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index a6d5530..80904ed 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -75,13 +75,15 @@ static int __init emu_setup_memblk(struct numa_meminfo *ei,
 
 /*
  * Sets up nr_nodes fake nodes interleaved over physical nodes ranging from addr
- * to max_addr.  The return value is the number of nodes allocated.
+ * to max_addr.
+ *
+ * Returns zero on success or negative on error.
  */
 static int __init split_nodes_interleave(struct numa_meminfo *ei,
 					 struct numa_meminfo *pi,
 					 u64 addr, u64 max_addr, int nr_nodes)
 {
-	nodemask_t physnode_mask = NODE_MASK_NONE;
+	nodemask_t physnode_mask = numa_nodes_parsed;
 	u64 size;
 	int big;
 	int nid = 0;
@@ -116,9 +118,6 @@ static int __init split_nodes_interleave(struct numa_meminfo *ei,
 		return -1;
 	}
 
-	for (i = 0; i < pi->nr_blks; i++)
-		node_set(pi->blk[i].nid, physnode_mask);
-
 	/*
 	 * Continue to fill physical nodes with fake nodes until there is no
 	 * memory left on any of them.
@@ -200,13 +199,15 @@ static u64 __init find_end_of_node(u64 start, u64 max_addr, u64 size)
 
 /*
  * Sets up fake nodes of `size' interleaved over physical nodes ranging from
- * `addr' to `max_addr'.  The return value is the number of nodes allocated.
+ * `addr' to `max_addr'.
+ *
+ * Returns zero on success or negative on error.
  */
 static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 					      struct numa_meminfo *pi,
 					      u64 addr, u64 max_addr, u64 size)
 {
-	nodemask_t physnode_mask = NODE_MASK_NONE;
+	nodemask_t physnode_mask = numa_nodes_parsed;
 	u64 min_size;
 	int nid = 0;
 	int i, ret;
@@ -231,9 +232,6 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 	}
 	size &= FAKE_NODE_MIN_HASH_MASK;
 
-	for (i = 0; i < pi->nr_blks; i++)
-		node_set(pi->blk[i].nid, physnode_mask);
-
 	/*
 	 * Fill physical nodes with fake nodes of size until there is no memory
 	 * left on any of them.

[PATCH V3 3/3] x86/numa_emulation: restructures numa_nodes_parsed from emulated nodes

[Wei Yang]

By emulating numa, it may contains more or less nodes than physical nodes.
In numa_emulation(), numa_meminfo/numa_distance/__apicid_to_node is
restructured according to emulated nodes, except numa_nodes_parsed.

This patch restructures numa_nodes_parsed from emulated nodes.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
---
 arch/x86/mm/numa_emulation.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index 80904ede2e7f..d805162e6045 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -395,6 +395,13 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 	/* commit */
 	*numa_meminfo = ei;
 
+	/* Make sure numa_nodes_parsed only contains emulated nodes */
+	nodes_clear(numa_nodes_parsed);
+	for (i = 0; i < ARRAY_SIZE(ei.blk); i++)
+		if (ei.blk[i].start != ei.blk[i].end &&
+		    ei.blk[i].nid != NUMA_NO_NODE)
+			node_set(ei.blk[i].nid, numa_nodes_parsed);
+
 	/*
 	 * Transform __apicid_to_node table to use emulated nids by
 	 * reverse-mapping phys_nid.  The maps should always exist but fall
-- 
2.11.0

[tip:x86/debug] x86/numa_emulation: Recalculate numa_nodes_parsed from emulated nodes

[tip-bot for Wei Yang]

Commit-ID:  4f167201edda7cd7525cc7f23944731ef5dd99a8
Gitweb:     http://git.kernel.org/tip/4f167201edda7cd7525cc7f23944731ef5dd99a8
Author:     Wei Yang <richard.weiyang@gmail.com>
AuthorDate: Sat, 8 Jul 2017 09:30:59 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 18 Jul 2017 11:16:49 +0200

x86/numa_emulation: Recalculate numa_nodes_parsed from emulated nodes

When emulating NUMA, the kernel's emulated NUMA configuration may contain
more or less nodes than there are physical nodes.

In numa_emulation(), we recalculate numa_meminfo/numa_distance/__apicid_to_node
according to the number of emulated nodes, except numa_nodes_parsed, which is
arguably an omission.

Recalculate numa_nodes_parsed as well.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bp@alien8.de
Cc: kirill@shutemov.name
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20170708013059.29708-4-richard.weiyang@gmail.com
[ Changelog fixes. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/numa_emulation.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index 80904ed..d805162 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -395,6 +395,13 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 	/* commit */
 	*numa_meminfo = ei;
 
+	/* Make sure numa_nodes_parsed only contains emulated nodes */
+	nodes_clear(numa_nodes_parsed);
+	for (i = 0; i < ARRAY_SIZE(ei.blk); i++)
+		if (ei.blk[i].start != ei.blk[i].end &&
+		    ei.blk[i].nid != NUMA_NO_NODE)
+			node_set(ei.blk[i].nid, numa_nodes_parsed);
+
 	/*
 	 * Transform __apicid_to_node table to use emulated nids by
 	 * reverse-mapping phys_nid.  The maps should always exist but fall