diff mbox series

[1/1] selftests: mm: hugepage-vmemmap fails on 64K page size systems.

Message ID 3b3a3ae37ba21218481c482a872bbf7526031600.1704865754.git.donettom@linux.vnet.ibm.com
State New
Headers
Series [1/1] selftests: mm: hugepage-vmemmap fails on 64K page size systems. |

Commit Message

Donet Tom Jan. 10, 2024, 8:33 a.m. UTC 
  The kernel sefltest mm/hugepage-vmemmap fails on architectures
which has different page size other than 4K. In hugepage-vmemmap
page size used is 4k so the pfn calculation will go wrong on systems
which has different page size .The length of MAP_HUGETLB memory must
be hugepage aligned but in hugepage-vmemmap map length is 2M so this
will not get aligned if the system has differnet hugepage size.

Added  psize() to get the page size and default_huge_page_size() to
get the default hugepage size at run time, hugepage-vmemmap test pass
on powerpc with 64K page size and x86 with 4K page size.

Result on powerpc without patch (page size 64K)
*# ./hugepage-vmemmap
Returned address is 0x7effff000000 whose pfn is 0
Head page flags (100000000) is invalid
check_page_flags: Invalid argument
*#

Result on powerpc with patch (page size 64K)
*# ./hugepage-vmemmap
Returned address is 0x7effff000000 whose pfn is 600
*#

Result on x86 with patch (page size 4K)
*# ./hugepage-vmemmap
Returned address is 0x7fc7c2c00000 whose pfn is 1dac00
*#

Signed-off-by: Donet Tom <donettom@linux.vnet.ibm.com>
Reported-by : Geetika Moolchandani (geetika@linux.ibm.com)
Tested-by : Geetika Moolchandani (geetika@linux.ibm.com)
---
 tools/testing/selftests/mm/hugepage-vmemmap.c | 29 ++++++++++++-------
 1 file changed, 18 insertions(+), 11 deletions(-)

Comments

Andrew Morton Jan. 10, 2024, 3:53 p.m. UTC | #1 
(cc Muchun)
On Wed, 10 Jan 2024 14:03:35 +0530 Donet Tom <donettom@linux.vnet.ibm.com> wrote:

> The kernel sefltest mm/hugepage-vmemmap fails on architectures
> which has different page size other than 4K. In hugepage-vmemmap
> page size used is 4k so the pfn calculation will go wrong on systems
> which has different page size .The length of MAP_HUGETLB memory must
> be hugepage aligned but in hugepage-vmemmap map length is 2M so this
> will not get aligned if the system has differnet hugepage size.
> 
> Added  psize() to get the page size and default_huge_page_size() to
> get the default hugepage size at run time, hugepage-vmemmap test pass
> on powerpc with 64K page size and x86 with 4K page size.
> 
> Result on powerpc without patch (page size 64K)
> *# ./hugepage-vmemmap
> Returned address is 0x7effff000000 whose pfn is 0
> Head page flags (100000000) is invalid
> check_page_flags: Invalid argument
> *#
> 
> Result on powerpc with patch (page size 64K)
> *# ./hugepage-vmemmap
> Returned address is 0x7effff000000 whose pfn is 600
> *#
> 
> Result on x86 with patch (page size 4K)
> *# ./hugepage-vmemmap
> Returned address is 0x7fc7c2c00000 whose pfn is 1dac00
> *#
> 
> Signed-off-by: Donet Tom <donettom@linux.vnet.ibm.com>
> Reported-by : Geetika Moolchandani (geetika@linux.ibm.com)
> Tested-by : Geetika Moolchandani (geetika@linux.ibm.com)

I'll add 

Fixes: b147c89cd429 ("selftests: vm: add a hugetlb test case")
Cc: <stable@vger.kernel.org>

> 
> diff --git a/tools/testing/selftests/mm/hugepage-vmemmap.c b/tools/testing/selftests/mm/hugepage-vmemmap.c
> index 5b354c209e93..894d28c3dd47 100644
> --- a/tools/testing/selftests/mm/hugepage-vmemmap.c
> +++ b/tools/testing/selftests/mm/hugepage-vmemmap.c
> @@ -10,10 +10,7 @@
>  #include <unistd.h>
>  #include <sys/mman.h>
>  #include <fcntl.h>
> -
> -#define MAP_LENGTH		(2UL * 1024 * 1024)
> -
> -#define PAGE_SIZE		4096
> +#include "vm_util.h"
>  
>  #define PAGE_COMPOUND_HEAD	(1UL << 15)
>  #define PAGE_COMPOUND_TAIL	(1UL << 16)
> @@ -39,6 +36,9 @@
>  #define MAP_FLAGS		(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
>  #endif
>  
> +static size_t pagesize;
> +static size_t maplength;
> +
>  static void write_bytes(char *addr, size_t length)
>  {
>  	unsigned long i;
> @@ -56,7 +56,7 @@ static unsigned long virt_to_pfn(void *addr)
>  	if (fd < 0)
>  		return -1UL;
>  
> -	lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET);
> +	lseek(fd, (unsigned long)addr / pagesize * sizeof(pagemap), SEEK_SET);
>  	read(fd, &pagemap, sizeof(pagemap));
>  	close(fd);
>  
> @@ -86,7 +86,7 @@ static int check_page_flags(unsigned long pfn)
>  	 * this also verifies kernel has correctly set the fake page_head to tail
>  	 * while hugetlb_free_vmemmap is enabled.
>  	 */
> -	for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) {
> +	for (i = 1; i < maplength / pagesize; i++) {
>  		read(fd, &pageflags, sizeof(pageflags));
>  		if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||
>  		    (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {
> @@ -106,18 +106,25 @@ int main(int argc, char **argv)
>  	void *addr;
>  	unsigned long pfn;
>  
> -	addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
> +	pagesize  = psize();
> +	maplength = default_huge_page_size();
> +	if (!maplength) {
> +		printf("Unable to determine huge page size\n");
> +		exit(1);
> +	}
> +
> +	addr = mmap(MAP_ADDR, maplength, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
>  	if (addr == MAP_FAILED) {
>  		perror("mmap");
>  		exit(1);
>  	}
>  
>  	/* Trigger allocation of HugeTLB page. */
> -	write_bytes(addr, MAP_LENGTH);
> +	write_bytes(addr, maplength);
>  
>  	pfn = virt_to_pfn(addr);
>  	if (pfn == -1UL) {
> -		munmap(addr, MAP_LENGTH);
> +		munmap(addr, maplength);
>  		perror("virt_to_pfn");
>  		exit(1);
>  	}
> @@ -125,13 +132,13 @@ int main(int argc, char **argv)
>  	printf("Returned address is %p whose pfn is %lx\n", addr, pfn);
>  
>  	if (check_page_flags(pfn) < 0) {
> -		munmap(addr, MAP_LENGTH);
> +		munmap(addr, maplength);
>  		perror("check_page_flags");
>  		exit(1);
>  	}
>  
>  	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
> -	if (munmap(addr, MAP_LENGTH)) {
> +	if (munmap(addr, maplength)) {
>  		perror("munmap");
>  		exit(1);
>  	}
> -- 
> 2.43.0
Muchun Song Jan. 11, 2024, 2:07 a.m. UTC | #2 
> On Jan 10, 2024, at 23:53, Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> (cc Muchun)
> On Wed, 10 Jan 2024 14:03:35 +0530 Donet Tom <donettom@linux.vnet.ibm.com> wrote:
> 
>> The kernel sefltest mm/hugepage-vmemmap fails on architectures
>> which has different page size other than 4K. In hugepage-vmemmap
>> page size used is 4k so the pfn calculation will go wrong on systems
>> which has different page size .The length of MAP_HUGETLB memory must
>> be hugepage aligned but in hugepage-vmemmap map length is 2M so this
>> will not get aligned if the system has differnet hugepage size.
>> 
>> Added  psize() to get the page size and default_huge_page_size() to
>> get the default hugepage size at run time, hugepage-vmemmap test pass
>> on powerpc with 64K page size and x86 with 4K page size.
>> 
>> Result on powerpc without patch (page size 64K)
>> *# ./hugepage-vmemmap
>> Returned address is 0x7effff000000 whose pfn is 0
>> Head page flags (100000000) is invalid
>> check_page_flags: Invalid argument
>> *#
>> 
>> Result on powerpc with patch (page size 64K)
>> *# ./hugepage-vmemmap
>> Returned address is 0x7effff000000 whose pfn is 600
>> *#
>> 
>> Result on x86 with patch (page size 4K)
>> *# ./hugepage-vmemmap
>> Returned address is 0x7fc7c2c00000 whose pfn is 1dac00
>> *#
>> 
>> Signed-off-by: Donet Tom <donettom@linux.vnet.ibm.com>
>> Reported-by : Geetika Moolchandani (geetika@linux.ibm.com)
>> Tested-by : Geetika Moolchandani (geetika@linux.ibm.com)

Acked-by: Muchun Song <muchun.song@linux.dev>

> 
> I'll add 
> 
> Fixes: b147c89cd429 ("selftests: vm: add a hugetlb test case")
> Cc: <stable@vger.kernel.org>

Yes. It should be a real bug fix.

Thanks.
diff mbox series

Patch

diff --git a/tools/testing/selftests/mm/hugepage-vmemmap.c b/tools/testing/selftests/mm/hugepage-vmemmap.c
index 5b354c209e93..894d28c3dd47 100644
--- a/tools/testing/selftests/mm/hugepage-vmemmap.c
+++ b/tools/testing/selftests/mm/hugepage-vmemmap.c
@@ -10,10 +10,7 @@ 
 #include <unistd.h>
 #include <sys/mman.h>
 #include <fcntl.h>
-
-#define MAP_LENGTH		(2UL * 1024 * 1024)
-
-#define PAGE_SIZE		4096
+#include "vm_util.h"
 
 #define PAGE_COMPOUND_HEAD	(1UL << 15)
 #define PAGE_COMPOUND_TAIL	(1UL << 16)
@@ -39,6 +36,9 @@ 
 #define MAP_FLAGS		(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
 #endif
 
+static size_t pagesize;
+static size_t maplength;
+
 static void write_bytes(char *addr, size_t length)
 {
 	unsigned long i;
@@ -56,7 +56,7 @@  static unsigned long virt_to_pfn(void *addr)
 	if (fd < 0)
 		return -1UL;
 
-	lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET);
+	lseek(fd, (unsigned long)addr / pagesize * sizeof(pagemap), SEEK_SET);
 	read(fd, &pagemap, sizeof(pagemap));
 	close(fd);
 
@@ -86,7 +86,7 @@  static int check_page_flags(unsigned long pfn)
 	 * this also verifies kernel has correctly set the fake page_head to tail
 	 * while hugetlb_free_vmemmap is enabled.
 	 */
-	for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) {
+	for (i = 1; i < maplength / pagesize; i++) {
 		read(fd, &pageflags, sizeof(pageflags));
 		if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||
 		    (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {
@@ -106,18 +106,25 @@  int main(int argc, char **argv)
 	void *addr;
 	unsigned long pfn;
 
-	addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
+	pagesize  = psize();
+	maplength = default_huge_page_size();
+	if (!maplength) {
+		printf("Unable to determine huge page size\n");
+		exit(1);
+	}
+
+	addr = mmap(MAP_ADDR, maplength, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
 	if (addr == MAP_FAILED) {
 		perror("mmap");
 		exit(1);
 	}
 
 	/* Trigger allocation of HugeTLB page. */
-	write_bytes(addr, MAP_LENGTH);
+	write_bytes(addr, maplength);
 
 	pfn = virt_to_pfn(addr);
 	if (pfn == -1UL) {
-		munmap(addr, MAP_LENGTH);
+		munmap(addr, maplength);
 		perror("virt_to_pfn");
 		exit(1);
 	}
@@ -125,13 +132,13 @@  int main(int argc, char **argv)
 	printf("Returned address is %p whose pfn is %lx\n", addr, pfn);
 
 	if (check_page_flags(pfn) < 0) {
-		munmap(addr, MAP_LENGTH);
+		munmap(addr, maplength);
 		perror("check_page_flags");
 		exit(1);
 	}
 
 	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
-	if (munmap(addr, MAP_LENGTH)) {
+	if (munmap(addr, maplength)) {
 		perror("munmap");
 		exit(1);
 	}