[RFC PATCH 3/4] hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel

[Nishanth Aravamudan <nacc@us.ibm.com>]

To keep /sys/kernel uncluttered, use the newly created /sys/kernel/mm as
the parent for the hugepage-controlling directories/files. Update the
ABI file and redirect the user to the more complete vm/hugetlbpage.txt
for details on hugepage usage.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>

---
Given the somewhat discombobulated state of hugetlbpage.txt, my next
step will be to clean it up and reorganize the information therein.

diff --git a/Documentation/ABI/testing/sysfs-kernel-hugepages b/Documentation/ABI/testing/sysfs-kernel-hugepages
deleted file mode 100644
index 3457747..0000000
--- a/Documentation/ABI/testing/sysfs-kernel-hugepages
+++ /dev/null
@@ -1,14 +0,0 @@
-What:		/sys/kernel/hugepages/
-Date:		June 2008
-Contact:	Nishanth Aravamudan <nacc@us.ibm.com>, hugetlb maintainers
-Description:
-		/sys/kernel/hugepages/ contains a number of subdirectories
-		of the form hugepages-<size>kb, where <size> is the page size
-		of the hugepages supported by the kernel/CPU combination.
-
-		Under these directories are a number of files:
-		nr_hugepages - minimum number of hugepages reserved
-		nr_overcommit_hugepages - maximum number that can be allocated
-		free_hugepages - number of hugepages free
-		surplus_hugepages -
-		resv_hugepages -
diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-hugepages b/Documentation/ABI/testing/sysfs-kernel-mm-hugepages
new file mode 100644
index 0000000..e21c005
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-hugepages
@@ -0,0 +1,15 @@
+What:		/sys/kernel/mm/hugepages/
+Date:		June 2008
+Contact:	Nishanth Aravamudan <nacc@us.ibm.com>, hugetlb maintainers
+Description:
+		/sys/kernel/mm/hugepages/ contains a number of subdirectories
+		of the form hugepages-<size>kB, where <size> is the page size
+		of the hugepages supported by the kernel/CPU combination.
+
+		Under these directories are a number of files:
+			nr_hugepages
+			nr_overcommit_hugepages
+			free_hugepages
+			surplus_hugepages
+			resv_hugepages
+		See Documentation/vm/hugetlbpage.txt for details.
diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
index 899b343..ea8714f 100644
--- a/Documentation/vm/hugetlbpage.txt
+++ b/Documentation/vm/hugetlbpage.txt
@@ -95,6 +95,29 @@ this condition holds, however, no more surplus huge pages will be
 allowed on the system until one of the two sysctls are increased
 sufficiently, or the surplus huge pages go out of use and are freed.
 
+With support for multiple hugepage pools at run-time available, much of
+the hugepage userspace interface has been duplicated in sysfs. The above
+information applies to the default hugepage size (which will be
+controlled by the proc interfaces for backwards compatibility). The root
+hugepage control directory is
+
+	/sys/kernel/mm/hugepages
+
+For each hugepage size supported by the running kernel, a subdirectory
+will exist, of the form
+
+	hugepages-${size}kB
+
+Inside each of these directories, the same set of files will exist:
+
+	nr_hugepages
+	nr_overcommit_hugepages
+	free_hugepages
+	resv_hugepages
+	surplus_hugepages
+
+which function as described above for the default hugepage-sized case.
+
 If the user applications are going to request hugepages using mmap system
 call, then it is required that system administrator mount a file system of
 type hugetlbfs:
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 14bfe17..9c24f8f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1258,7 +1258,7 @@ static void __init hugetlb_sysfs_init(void)
 	struct hstate *h;
 	int err;
 
-	hugepages_kobj = kobject_create_and_add("hugepages", kernel_kobj);
+	hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
 	if (!hugepages_kobj)
 		return;
 
-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center

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