memblock:fix validation of NUMA coverage

GIT PULL Merged Mike Rapoport 4 participants 8 messages Jun 13, 2024 – Jun 14, 2024

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Stable branch Memory management memblock and memory management initialization

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Mike Rapoport

author maintainer

2024-06-13 14:11 UTC #0 lore raw

Hi Linus,

The following changes since commit 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0:

Linux 6.10-rc1 (2024-05-26 15:20:12 -0700)

are available in the Git repository at:

https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock

for you to fetch changes up to 3ac36aa7307363b7247ccb6f6a804e11496b2b36:

x86/mm/numa: Use NUMA_NO_NODE when calling memblock_set_node() (2024-06-06 22:20:39 +0300)

----------------------------------------------------------------
Jan Beulich (2):
memblock: make memblock_set_node() also warn about use of MAX_NUMNODES x86/mm/numa: Use NUMA_NO_NODE when calling memblock_set_node()

 arch/x86/mm/numa.c | 6 +++---
 mm/memblock.c      | 4 ++++
 2 files changed, 7 insertions(+), 3 deletions(-)

Signature · 2 lines

Sincerely yours,
Mike.

Linus Torvalds

2024-06-13 17:09 UTC #1 lore raw

Quoted 2 lines · Mike Rapoport

https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock

What's going on? This is the second pull request recently that doesn't actually mention where to pull from.

I can do a "git ls-remote", and I see that you have a tag called "fixes-2024-06-13" that then points to the commit you mention:

Quoted 1 line

for you to fetch changes up to 3ac36aa7307363b7247ccb6f6a804e11496b2b36:

but that tag name isn't actually in the pull request.

Is there some broken scripting that people have started using (or have been using for a while and was recently broken)?

Linus

Linus Torvalds

2024-06-13 17:38 UTC #2 lore raw

Quoted 3 lines · Linus Torvalds

Is there some broken scripting that people have started using (or have been using for a while and was recently broken)?

... and then when I actually pull the code, I note that the problem where it checked _one_ bogus value has just been replaced with checking _another_ bogus value.

Christ.

What if people use a node ID that is simply outside the range entirely, instead of one of those special node IDs?

And now for memblock_set_node() you should apparently use NUMA_NO_NODE to not get a warning, but for memblock_set_region_node() apparently the right random constant to use is MAX_NUMNODES.

Does *any* of this make sense? No.

How about instead of having two random constants - and not having any range checking that I see - just have *one* random constant for "I have no range", call that NUMA_NO_NODE, and then have a simple helper for "do I have a valid range", and make that be

static inline bool numa_valid_node(int nid)
{ return (unsigned int)nid < MAX_NUMNODES; }

or something like that? Notice that now *all* of

- NUMA_NO_NODE (explicitly no node)

- MAX_NUMNODES (randomly used no node)

- out of range node (who knows wth firmware tables do?)

will get the same result from that "numa_valid_node()" function.

And at that point you don't need to care, you don't need to warn, and you don't need to have these insane rules where "sometimes you *HAVE* to use NUMA_NO_NODE, or we warn, in other cases MAX_NUMNODES is the thing".

Please? IOW, instead of adding a warning for fragile code, then change some caller to follow the new rules, JUST FIX THE STUPID FRAGILITY!

Or hey, just do

    #define NUMA_NO_NODE MAX_NUMNODES

and have two names for the *same* constant, instead fo having two different constants with strange semantic differences that seem to make no sense and where the memblock code itself seems to go back-and-forth on it in different contexts.

Linus

Jan Beulich

2024-06-14 06:01 UTC #3 lore raw

Quoted 19 lines · Linus Torvalds

Quoted 3 lines · Linus Torvalds
Is there some broken scripting that people have started using (or have been using for a while and was recently broken)?
... and then when I actually pull the code, I note that the problem where it checked _one_ bogus value has just been replaced with checking _another_ bogus value.
Christ.
What if people use a node ID that is simply outside the range entirely, instead of one of those special node IDs?
And now for memblock_set_node() you should apparently use NUMA_NO_NODE to not get a warning, but for memblock_set_region_node() apparently the right random constant to use is MAX_NUMNODES.

Quoted 5 lines

Does *any* of this make sense? No.
How about instead of having two random constants - and not having any range checking that I see - just have *one* random constant for "I have no range", call that NUMA_NO_NODE,

Just to mention it - my understanding is that this is an ongoing process heading in this very direction. I'm not an mm person at all, so I can't tell why the conversion wasn't done / can't be done all in one go.

Jan

Quoted 34 lines

and then have a simple helper
for "do I have a valid range", and make that be
static inline bool numa_valid_node(int nid)
{ return (unsigned int)nid < MAX_NUMNODES; }
or something like that? Notice that now *all* of
- NUMA_NO_NODE (explicitly no node)
- MAX_NUMNODES (randomly used no node)
- out of range node (who knows wth firmware tables do?)
will get the same result from that "numa_valid_node()" function.
And at that point you don't need to care, you don't need to warn, and you don't need to have these insane rules where "sometimes you *HAVE* to use NUMA_NO_NODE, or we warn, in other cases MAX_NUMNODES is the thing".
Please? IOW, instead of adding a warning for fragile code, then change some caller to follow the new rules, JUST FIX THE STUPID FRAGILITY!
Or hey, just do
    #define NUMA_NO_NODE MAX_NUMNODES
and have two names for the *same* constant, instead fo having two different constants with strange semantic differences that seem to make no sense and where the memblock code itself seems to go back-and-forth on it in different contexts.
Linus

Mike Rapoport

author maintainer

2024-06-14 07:33 UTC #4 lore raw

Quoted 22 lines · Jan Beulich

Quoted 21 lines · Linus Torvalds
Quoted 3 lines · Linus Torvalds
Is there some broken scripting that people have started using (or have been using for a while and was recently broken)?
... and then when I actually pull the code, I note that the problem where it checked _one_ bogus value has just been replaced with checking _another_ bogus value.
Christ.
What if people use a node ID that is simply outside the range entirely, instead of one of those special node IDs?
And now for memblock_set_node() you should apparently use NUMA_NO_NODE to not get a warning, but for memblock_set_region_node() apparently the right random constant to use is MAX_NUMNODES.
Does *any* of this make sense? No.

Quoted 7 lines

Quoted 3 lines
How about instead of having two random constants - and not having any range checking that I see - just have *one* random constant for "I have no range", call that NUMA_NO_NODE,
Just to mention it - my understanding is that this is an ongoing process heading in this very direction. I'm not an mm person at all, so I can't tell why the conversion wasn't done / can't be done all in one go.

Nah, it's an historical mess and my oversight.

Quoted 1 line

Jan

Signature · 2 lines

Sincerely yours,
Mike.

Mike Rapoport

author maintainer

2024-06-14 08:20 UTC #5 lore raw

In reply to Linus Torvalds

Quoted 47 lines · Linus Torvalds

Quoted 3 lines · Linus Torvalds
Is there some broken scripting that people have started using (or have been using for a while and was recently broken)?
... and then when I actually pull the code, I note that the problem where it checked _one_ bogus value has just been replaced with checking _another_ bogus value.
Christ.
What if people use a node ID that is simply outside the range entirely, instead of one of those special node IDs?
And now for memblock_set_node() you should apparently use NUMA_NO_NODE to not get a warning, but for memblock_set_region_node() apparently the right random constant to use is MAX_NUMNODES.
Does *any* of this make sense? No.
How about instead of having two random constants - and not having any range checking that I see - just have *one* random constant for "I have no range", call that NUMA_NO_NODE, and then have a simple helper for "do I have a valid range", and make that be
static inline bool numa_valid_node(int nid)
{ return (unsigned int)nid < MAX_NUMNODES; }
or something like that? Notice that now *all* of
- NUMA_NO_NODE (explicitly no node)
- MAX_NUMNODES (randomly used no node)
- out of range node (who knows wth firmware tables do?)
will get the same result from that "numa_valid_node()" function.
And at that point you don't need to care, you don't need to warn, and you don't need to have these insane rules where "sometimes you *HAVE* to use NUMA_NO_NODE, or we warn, in other cases MAX_NUMNODES is the thing".
Please? IOW, instead of adding a warning for fragile code, then change some caller to follow the new rules, JUST FIX THE STUPID FRAGILITY!

Quoted 8 lines

Or hey, just do
    #define NUMA_NO_NODE MAX_NUMNODES
and have two names for the *same* constant, instead fo having two different constants with strange semantic differences that seem to make no sense and where the memblock code itself seems to go back-and-forth on it in different contexts.

A single constant is likely to backfire because I remember seeing checks like 'if (nid < 0)' so redefining NUMA_NO_NODE will require auditing all those.

But a helper function works great.
I could only lightly test it as I don't have a fleet of machines with variety of memory layouts, so I'm planning to push it into -next early next week (with subject replaced by a more informative one)

From 319eddd74b372cae840782c7d53832ab30533a6b Mon Sep 17 00:00:00 2001
From: "Mike Rapoport (IBM)" <[email protected]>
Date: Fri, 14 Jun 2024 11:05:43 +0300
Subject: [PATCH] memblock: FIX THE STUPID FRAGILITY

Introduce numa_valid_node(nid) that verifies that nid is a valid node ID and use that instead of comparing nid parameter with either NUMA_NO_NODE or MAX_NUMNODES.

This makes the checks for valid node IDs consistent and more robust and allows to get rid of multiple WARNings.

Signed-off-by Mike Rapoport (IBM) <[email protected]>

---
 include/linux/numa.h |  5 +++++
 mm/memblock.c        | 28 +++++++---------------------
 2 files changed, 12 insertions(+), 21 deletions(-)

include/linux/numa.h +5 -0

index 1d43371fafd2..eb19503604fe 100644
@@ -15,6 +15,11 @@
 #define	NUMA_NO_NODE	(-1)
 #define	NUMA_NO_MEMBLK	(-1)
 
+static inline bool numa_valid_node(int nid)
+{
+	return nid >= 0 && nid < MAX_NUMNODES;
+}
+
 /* optionally keep NUMA memory info available post init */
 #ifdef CONFIG_NUMA_KEEP_MEMINFO
 #define __initdata_or_meminfo

mm/memblock.c +7 ~~-21~~

index 08e9806b1cf9..e81fb68f7f88 100644
@@ -754,7 +754,7 @@ bool __init_memblock memblock_validate_numa_coverage(unsigned long threshold_byt
 
 	/* calculate lose page */
 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
-		if (nid == NUMA_NO_NODE)
+		if (!numa_valid_node(nid))
 			nr_pages += end_pfn - start_pfn;
 	}

@@ -1061,7 +1061,7 @@ static bool should_skip_region(struct memblock_type *type,
 		return false;
 
 	/* only memory regions are associated with nodes, check it */
-	if (nid != NUMA_NO_NODE && nid != m_nid)
+	if (numa_valid_node(nid) && nid != m_nid)
 		return true;
 
 	/* skip hotpluggable memory regions if needed */

@@ -1118,10 +1118,6 @@ void __next_mem_range(u64 *idx, int nid, enum memblock_flags flags,
 	int idx_a = *idx & 0xffffffff;
 	int idx_b = *idx >> 32;
 
-	if (WARN_ONCE(nid == MAX_NUMNODES,
-	"Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
-		nid = NUMA_NO_NODE;
-
 	for (; idx_a < type_a->cnt; idx_a++) {
 		struct memblock_region *m = &type_a->regions[idx_a];

@@ -1215,9 +1211,6 @@ void __init_memblock __next_mem_range_rev(u64 *idx, int nid,
 	int idx_a = *idx & 0xffffffff;
 	int idx_b = *idx >> 32;
 
-	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
-		nid = NUMA_NO_NODE;
-
 	if (*idx == (u64)ULLONG_MAX) {
 		idx_a = type_a->cnt - 1;
 		if (type_b != NULL)

@@ -1303,7 +1296,7 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
 
 		if (PFN_UP(r->base) >= PFN_DOWN(r->base + r->size))
 			continue;
-		if (nid == MAX_NUMNODES || nid == r_nid)
+		if (!numa_valid_node(nid) || nid == r_nid)
 			break;
 	}
 	if (*idx >= type->cnt) {

@@ -1339,10 +1332,6 @@ int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size,
 	int start_rgn, end_rgn;
 	int i, ret;
 
-	if (WARN_ONCE(nid == MAX_NUMNODES,
-		      "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
-		nid = NUMA_NO_NODE;
-
 	ret = memblock_isolate_range(type, base, size, &start_rgn, &end_rgn);
 	if (ret)
 		return ret;

@@ -1452,9 +1441,6 @@ phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
 	enum memblock_flags flags = choose_memblock_flags();
 	phys_addr_t found;
 
-	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
-		nid = NUMA_NO_NODE;
-
 	if (!align) {
 		/* Can't use WARNs this early in boot on powerpc */
 		dump_stack();

@@ -1467,7 +1453,7 @@ phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
 	if (found && !memblock_reserve(found, size))
 		goto done;
 
-	if (nid != NUMA_NO_NODE && !exact_nid) {
+	if (numa_valid_node(nid) && !exact_nid) {
 		found = memblock_find_in_range_node(size, align, start,
 						    end, NUMA_NO_NODE,
 						    flags);

@@ -1987,7 +1973,7 @@ static void __init_memblock memblock_dump(struct memblock_type *type)
 		end = base + size - 1;
 		flags = rgn->flags;
 #ifdef CONFIG_NUMA
-		if (memblock_get_region_node(rgn) != MAX_NUMNODES)
+		if (numa_valid_node(memblock_get_region_node(rgn)))
 			snprintf(nid_buf, sizeof(nid_buf), " on node %d",
 				 memblock_get_region_node(rgn));
 #endif

@@ -2181,7 +2167,7 @@ static void __init memmap_init_reserved_pages(void)
 			start = region->base;
 			end = start + region->size;
 
-			if (nid == NUMA_NO_NODE || nid >= MAX_NUMNODES)
+			if (!numa_valid_node(nid))
 				nid = early_pfn_to_nid(PFN_DOWN(start));
 
 			reserve_bootmem_region(start, end, nid);

@@ -2272,7 +2258,7 @@ static int memblock_debug_show(struct seq_file *m, void *private)
 
 		seq_printf(m, "%4d: ", i);
 		seq_printf(m, "%pa..%pa ", &reg->base, &end);
-		if (nid != MAX_NUMNODES)
+		if (numa_valid_node(nid))
 			seq_printf(m, "%4d ", nid);
 		else
 			seq_printf(m, "%4c ", 'x');

Signature · 1 line

2.43.0

Quoted 1 line

Linus

Signature · 2 lines

Sincerely yours,
Mike.

Linus Torvalds

2024-06-14 16:28 UTC #6 lore raw

Quoted 4 lines · Mike Rapoport

A single constant is likely to backfire because I remember seeing checks like 'if (nid < 0)' so redefining NUMA_NO_NODE will require auditing all those.

Yeah, fair enough.

Quoted 1 line

But a helper function works great.

Thanks, that patch looks like a nice improvement to me.

Linus

[email protected]

merge bot Merged

2024-06-13 19:30 UTC #7 lore raw

In reply to Mike Rapoport

The pull request you sent on Thu, 13 Jun 2024 17:09:36 +0300:

Quoted 1 line

https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock refs/heads/master

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/3572597ca844f625a3c9ba629ed0872b64c16179

Thank you!

Signature · 2 lines

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