Re: [PATCH] mm/hugetlb: Warn the user when issues arise on boot due to hugepages

[Andrew Morton <akpm@linux-foundation.org>]

On Fri,  2 Jun 2017 20:54:13 -0400 "Liam R. Howlett" <Liam.Howlett@Oracle.com> wrote:

> When the user specifies too many hugepages or an invalid
> default_hugepagesz the communication to the user is implicit in the
> allocation message.  This patch adds a warning when the desired page
> count is not allocated and prints an error when the default_hugepagesz
> is invalid on boot.
> 
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -70,6 +70,7 @@ struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
>  
>  /* Forward declaration */
>  static int hugetlb_acct_memory(struct hstate *h, long delta);
> +static char * __init memfmt(char *buf, unsigned long n);

It's better to just move memfmt() to the right place.  After all, you
have revealed that it was in the wrong place, no?

(Am a bit surprised that something as general as memfmt is private to
hugetlb.c)

--- a/mm/hugetlb.c~mm-hugetlb-warn-the-user-when-issues-arise-on-boot-due-to-hugepages-fix
+++ a/mm/hugetlb.c
@@ -69,7 +69,17 @@ struct mutex *hugetlb_fault_mutex_table
 
 /* Forward declaration */
 static int hugetlb_acct_memory(struct hstate *h, long delta);
-static char * __init memfmt(char *buf, unsigned long n);
+
+static char * __init memfmt(char *buf, unsigned long n)
+{
+	if (n >= (1UL << 30))
+		sprintf(buf, "%lu GB", n >> 30);
+	else if (n >= (1UL << 20))
+		sprintf(buf, "%lu MB", n >> 20);
+	else
+		sprintf(buf, "%lu KB", n >> 10);
+	return buf;
+}
 
 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
 {
@@ -2238,17 +2248,6 @@ static void __init hugetlb_init_hstates(
 	VM_BUG_ON(minimum_order == UINT_MAX);
 }
 
-static char * __init memfmt(char *buf, unsigned long n)
-{
-	if (n >= (1UL << 30))
-		sprintf(buf, "%lu GB", n >> 30);
-	else if (n >= (1UL << 20))
-		sprintf(buf, "%lu MB", n >> 20);
-	else
-		sprintf(buf, "%lu KB", n >> 10);
-	return buf;
-}
-
 static void __init report_hugepages(void)
 {
 	struct hstate *h;
_

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