linux-kernel - [PATCH v2 16/28] mm/hugetlb: deal with multiple calls to hugetlb_bootmem

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Message-ID: <20250129224157.2046079-17-fvdl@google.com>
Date: Wed, 29 Jan 2025 22:41:45 +0000
From: Frank van der Linden <fvdl@...gle.com>
To: akpm@...ux-foundation.org, muchun.song@...ux.dev, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Cc: yuzhao@...gle.com, usamaarif642@...il.com, joao.m.martins@...cle.com, 
	roman.gushchin@...ux.dev, Frank van der Linden <fvdl@...gle.com>
Subject: [PATCH v2 16/28] mm/hugetlb: deal with multiple calls to hugetlb_bootmem_alloc

Architectures that want pre-HVO of hugetlb vmemmap pages
will need to call hugetlb_bootmem_alloc from an earlier
spot in boot (before sparse_init). To facilitate some
architectures doing this, protect hugetlb_bootmem_alloc
against multiple calls.

Also provide a helper function to check if it's been called,
so that the early HVO code, to be added later, can see if there
is anything to do.

Signed-off-by: Frank van der Linden <fvdl@...gle.com>
---
 include/linux/hugetlb.h |  6 ++++++
 mm/hugetlb.c            | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 9cd7c9dacb88..5061279e5f73 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -175,6 +175,7 @@ extern int sysctl_hugetlb_shm_group;
 extern struct list_head huge_boot_pages[MAX_NUMNODES];
 
 void hugetlb_bootmem_alloc(void);
+bool hugetlb_bootmem_allocated(void);
 
 /* arch callbacks */
 
@@ -1256,6 +1257,11 @@ static inline bool hugetlbfs_pagecache_present(
 static inline void hugetlb_bootmem_alloc(void)
 {
 }
+
+static inline bool hugetlb_bootmem_allocated(void)
+{
+	return false;
+}
 #endif	/* CONFIG_HUGETLB_PAGE */
 
 static inline spinlock_t *huge_pte_lock(struct hstate *h,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a0a87d1a8569..0a27659d9290 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4911,16 +4911,28 @@ static int __init default_hugepagesz_setup(char *s)
 }
 hugetlb_early_param("default_hugepagesz", default_hugepagesz_setup);
 
+static bool __hugetlb_bootmem_allocated __initdata;
+
+bool __init hugetlb_bootmem_allocated(void)
+{
+	return __hugetlb_bootmem_allocated;
+}
+
 void __init hugetlb_bootmem_alloc(void)
 {
 	struct hstate *h;
 
+	if (__hugetlb_bootmem_allocated)
+		return;
+
 	hugetlb_parse_params();
 
 	for_each_hstate(h) {
 		if (hstate_is_gigantic(h))
 			hugetlb_hstate_alloc_pages(h);
 	}
+
+	__hugetlb_bootmem_allocated = true;
 }
 
 static unsigned int allowed_mems_nr(struct hstate *h)
-- 
2.48.1.262.g85cc9f2d1e-goog