From: Claudio Imbrenda <imbrenda@linux.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org,
frankja@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com,
david@redhat.com, linux-mm@kvack.org,
Uladzislau Rezki <urezki@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
David Rientjes <rientjes@google.com>,
Christoph Hellwig <hch@infradead.org>
Subject: [PATCH v4 1/2] mm/vmalloc: add vmalloc_no_huge
Date: Mon, 14 Jun 2021 15:23:56 +0200 [thread overview]
Message-ID: <20210614132357.10202-2-imbrenda@linux.ibm.com> (raw)
In-Reply-To: <20210614132357.10202-1-imbrenda@linux.ibm.com>
Commit 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") added
support for hugepage vmalloc mappings, it also added the flag
VM_NO_HUGE_VMAP for __vmalloc_node_range to request the allocation to
be performed with 0-order non-huge pages. This flag is not accessible
when calling vmalloc, the only option is to call directly
__vmalloc_node_range, which is not exported.
This means that a module can't vmalloc memory with small pages.
Case in point: KVM on s390x needs to vmalloc a large area, and it needs
to be mapped with non-huge pages, because of a hardware limitation.
This patch adds the function vmalloc_no_huge, which works like vmalloc,
but it is guaranteed to always back the mapping using small pages. This
new function is exported, therefore it is usable by modules.
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
---
include/linux/vmalloc.h | 1 +
mm/vmalloc.c | 16 ++++++++++++++++
2 files changed, 17 insertions(+)
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 4d668abb6391..bfaaf0b6fa76 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -135,6 +135,7 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
const void *caller);
void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
int node, const void *caller);
+void *vmalloc_no_huge(unsigned long size);
extern void vfree(const void *addr);
extern void vfree_atomic(const void *addr);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a13ac524f6ff..296a2fcc3fbe 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2998,6 +2998,22 @@ void *vmalloc(unsigned long size)
}
EXPORT_SYMBOL(vmalloc);
+/**
+ * vmalloc_no_huge - allocate virtually contiguous memory using small pages
+ * @size: allocation size
+ *
+ * Allocate enough non-huge pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ *
+ * Return: pointer to the allocated memory or %NULL on error
+ */
+void *vmalloc_no_huge(unsigned long size)
+{
+ return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, GFP_KERNEL, PAGE_KERNEL,
+ VM_NO_HUGE_VMAP, NUMA_NO_NODE, __builtin_return_address(0));
+}
+EXPORT_SYMBOL(vmalloc_no_huge);
+
/**
* vzalloc - allocate virtually contiguous memory with zero fill
* @size: allocation size
--
2.31.1
next prev parent reply other threads:[~2021-06-14 13:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 13:23 [PATCH v4 0/2] mm: add vmalloc_no_huge and use it Claudio Imbrenda
2021-06-14 13:23 ` Claudio Imbrenda [this message]
2021-06-14 13:44 ` [PATCH v4 1/2] mm/vmalloc: add vmalloc_no_huge David Hildenbrand
2021-06-14 13:55 ` Uladzislau Rezki
2021-06-14 15:21 ` Christoph Hellwig
2021-06-18 19:47 ` David Rientjes
2021-06-14 13:23 ` [PATCH v4 2/2] KVM: s390: prepare for hugepage vmalloc Claudio Imbrenda
2021-06-14 13:44 ` David Hildenbrand
2021-06-14 23:59 ` [PATCH v4 0/2] mm: add vmalloc_no_huge and use it Andrew Morton
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