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mm: hugetlb: fix per-node size calculation for hugetlb_cma

PATCH Superseded Roman Gushchin 1 participant 3 messages Mar 23, 2020

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Memory management HugeTLB
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Roman Gushchin

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#0 lore raw

PATCH 1/1 mm: hugetlb: fix per-node size calculation for hugetlb_cma

Aslan found a bug in the per-node hugetlb_cma area size calculation:
the total remaining size should cap the per-node area size instead of be the minimal possible allocation.

Without the fix:

[    0.004136] hugetlb_cma: reserve 2048 MiB, up to 1024 MiB per node
[    0.004138] cma: Reserved 2048 MiB at 0x0000000180000000
[    0.004139] hugetlb_cma: reserved 2048 MiB on node 0

With the fix:

[    0.006780] hugetlb_cma: reserve 2048 MiB, up to 1024 MiB per node
[    0.006786] cma: Reserved 1024 MiB at 0x00000001c0000000
[    0.006787] hugetlb_cma: reserved 1024 MiB on node 0
[    0.006788] cma: Reserved 1024 MiB at 0x00000003c0000000
[    0.006789] hugetlb_cma: reserved 1024 MiB on node 1
Reported-by Aslan Barkirov <[email protected]>
Signed-off-by Roman Gushchin <[email protected]>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
mm/hugetlb.c +1 -1
index 456f4c010fea..44b47c2b6fab 100644
@@ -5590,7 +5590,7 @@ void __init hugetlb_cma_reserve(int order)
 		min_pfn = min_low_pfn;
 		max_pfn = max_low_pfn;
 #endif
-		size = max(per_node, hugetlb_cma_size - reserved);
+		size = min(per_node, hugetlb_cma_size - reserved);
 		size = round_up(size, PAGE_SIZE << order);
 
 		if (size > ((max_pfn - min_pfn) << PAGE_SHIFT) / 2) {
Signature · 1 line
2.25.1
author
#1 lore raw

PATCH v2 1/1 mm: hugetlb: fix per-node size calculation for hugetlb_cma

Aslan found a bug in the per-node hugetlb_cma area size calculation:
the total remaining size should cap the per-node area size instead of be the minimal possible allocation.

Without the fix:

[    0.004136] hugetlb_cma: reserve 2048 MiB, up to 1024 MiB per node
[    0.004138] cma: Reserved 2048 MiB at 0x0000000180000000
[    0.004139] hugetlb_cma: reserved 2048 MiB on node 0

With the fix:

[    0.006780] hugetlb_cma: reserve 2048 MiB, up to 1024 MiB per node
[    0.006786] cma: Reserved 1024 MiB at 0x00000001c0000000
[    0.006787] hugetlb_cma: reserved 1024 MiB on node 0
[    0.006788] cma: Reserved 1024 MiB at 0x00000003c0000000
[    0.006789] hugetlb_cma: reserved 1024 MiB on node 1
Reported-by Aslan Bakirov <[email protected]>
Signed-off-by Roman Gushchin <[email protected]>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
mm/hugetlb.c +1 -1
index 456f4c010fea..44b47c2b6fab 100644
@@ -5590,7 +5590,7 @@ void __init hugetlb_cma_reserve(int order)
 		min_pfn = min_low_pfn;
 		max_pfn = max_low_pfn;
 #endif
-		size = max(per_node, hugetlb_cma_size - reserved);
+		size = min(per_node, hugetlb_cma_size - reserved);
 		size = round_up(size, PAGE_SIZE << order);
 
 		if (size > ((max_pfn - min_pfn) << PAGE_SHIFT) / 2) {
Signature · 1 line
2.25.1
author
#2 lore raw
In reply to Roman Gushchin
Quoted 10 lines · Roman Gushchin

Aslan found a bug in the per-node hugetlb_cma area size calculation:
the total remaining size should cap the per-node area size instead of be the minimal possible allocation.

Without the fix:

[    0.004136] hugetlb_cma: reserve 2048 MiB, up to 1024 MiB per node
[    0.004138] cma: Reserved 2048 MiB at 0x0000000180000000
[    0.004139] hugetlb_cma: reserved 2048 MiB on node 0

With the fix:

Quoted 8 lines
[    0.006780] hugetlb_cma: reserve 2048 MiB, up to 1024 MiB per node
[    0.006786] cma: Reserved 1024 MiB at 0x00000001c0000000
[    0.006787] hugetlb_cma: reserved 1024 MiB on node 0
[    0.006788] cma: Reserved 1024 MiB at 0x00000003c0000000
[    0.006789] hugetlb_cma: reserved 1024 MiB on node 1
Reported-by Aslan Barkirov <[email protected]>
Signed-off-by Roman Gushchin <[email protected]>

I'm deeply sorry, I've made a typo in Aslan's name.

v2 fixes this.

Thanks!