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mm/gup_test: keep longterm pin state per file

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The pin longterm test currently stores its data globally, shared among
multiple concurrent users of the interface (multiple open file descriptors
-> multiple "struct file"'s).  That makes the gup_test interface
problematic to use concurrently: two users, such as concurrent selftest
runs, can interfere with the same longterm pin state.

While this has not been observed as a problem so far in practice, let's
just handle it cleanly.  There could be a way to trigger selftest failures
by e.g., running the cow.c and gup_longerm.c selftests concurrently, but
we usually run them sequentially.  Let's add a "Fixes" tag to be safe, but
not need to CC stable.

Link: https://lore.kernel.org/20260810-gup_test_data-v1-1-fb1d41be5bb4@kernel.org
Fixes: c77369b437 ("mm/gup_test: start/stop/read functionality for PIN LONGTERM test")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reported-by: yunhui cui <cuiyunhui@bytedance.com>
Closes: https://lore.kernel.org/r/20260608025043.88087-1-cuiyunhui@bytedance.com
Tested-by: Yunhui Cui <cuiyunhui@bytedance.com>
Tested-by: Lance Yang <lance.yang@linux.dev>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand (Arm) 2026-08-10 13:31:14 +02:00 committed by Andrew Morton
parent 8790303cba
commit 534b19bbb6
1 changed files with 62 additions and 32 deletions
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94
mm/gup_test.c
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@ -8,6 +8,12 @@
#include <linux/highmem.h>
#include "gup_test.h"
struct gup_test_data {
struct mutex longterm_mutex;
struct page **longterm_pages;
unsigned long longterm_nr_pages;
};
static void put_back_pages(unsigned int cmd, struct page **pages,
unsigned long nr_pages, unsigned int gup_test_flags)
{
@ -208,23 +214,20 @@ static int __gup_test_ioctl(unsigned int cmd,
return ret;
}
static DEFINE_MUTEX(pin_longterm_test_mutex);
static struct page **pin_longterm_test_pages;
static unsigned long pin_longterm_test_nr_pages;
static inline void pin_longterm_test_stop(void)
static inline void pin_longterm_test_stop(struct gup_test_data *data)
{
if (pin_longterm_test_pages) {
if (pin_longterm_test_nr_pages)
unpin_user_pages(pin_longterm_test_pages,
pin_longterm_test_nr_pages);
kvfree(pin_longterm_test_pages);
pin_longterm_test_pages = NULL;
pin_longterm_test_nr_pages = 0;
if (data->longterm_pages) {
if (data->longterm_nr_pages)
unpin_user_pages(data->longterm_pages,
data->longterm_nr_pages);
kvfree(data->longterm_pages);
data->longterm_pages = NULL;
data->longterm_nr_pages = 0;
}
}
static inline int pin_longterm_test_start(unsigned long arg)
static inline int pin_longterm_test_start(struct gup_test_data *data,
unsigned long arg)
{
long nr_pages, cur_pages, addr, remaining_pages;
int gup_flags = FOLL_LONGTERM;
@ -233,7 +236,7 @@ static inline int pin_longterm_test_start(unsigned long arg)
int ret = 0;
bool fast;
if (pin_longterm_test_pages)
if (data->longterm_pages)
return -EINVAL;
if (copy_from_user(&args, (void __user *)arg, sizeof(args)))
@ -263,12 +266,12 @@ static inline int pin_longterm_test_start(unsigned long arg)
return -EINTR;
}
pin_longterm_test_pages = pages;
pin_longterm_test_nr_pages = 0;
data->longterm_pages = pages;
data->longterm_nr_pages = 0;
while (nr_pages - pin_longterm_test_nr_pages) {
remaining_pages = nr_pages - pin_longterm_test_nr_pages;
addr = args.addr + pin_longterm_test_nr_pages * PAGE_SIZE;
while (nr_pages - data->longterm_nr_pages) {
remaining_pages = nr_pages - data->longterm_nr_pages;
addr = args.addr + data->longterm_nr_pages * PAGE_SIZE;
if (fast)
cur_pages = pin_user_pages_fast(addr, remaining_pages,
@ -277,11 +280,11 @@ static inline int pin_longterm_test_start(unsigned long arg)
cur_pages = pin_user_pages(addr, remaining_pages,
gup_flags, pages);
if (cur_pages < 0) {
pin_longterm_test_stop();
pin_longterm_test_stop(data);
ret = cur_pages;
break;
}
pin_longterm_test_nr_pages += cur_pages;
data->longterm_nr_pages += cur_pages;
pages += cur_pages;
}
@ -290,19 +293,20 @@ static inline int pin_longterm_test_start(unsigned long arg)
return ret;
}
static inline int pin_longterm_test_read(unsigned long arg)
static inline int pin_longterm_test_read(struct gup_test_data *data,
unsigned long arg)
{
__u64 user_addr;
unsigned long i;
if (!pin_longterm_test_pages)
if (!data->longterm_pages)
return -EINVAL;
if (copy_from_user(&user_addr, (void __user *)arg, sizeof(user_addr)))
return -EFAULT;
for (i = 0; i < pin_longterm_test_nr_pages; i++) {
void *addr = kmap_local_page(pin_longterm_test_pages[i]);
for (i = 0; i < data->longterm_nr_pages; i++) {
void *addr = kmap_local_page(data->longterm_pages[i]);
unsigned long ret;
ret = copy_to_user((void __user *)(unsigned long)user_addr, addr,
@ -318,25 +322,26 @@ static inline int pin_longterm_test_read(unsigned long arg)
static long pin_longterm_test_ioctl(struct file *filep, unsigned int cmd,
unsigned long arg)
{
struct gup_test_data *data = filep->private_data;
int ret = -EINVAL;
if (mutex_lock_killable(&pin_longterm_test_mutex))
if (mutex_lock_killable(&data->longterm_mutex))
return -EINTR;
switch (cmd) {
case PIN_LONGTERM_TEST_START:
ret = pin_longterm_test_start(arg);
ret = pin_longterm_test_start(data, arg);
break;
case PIN_LONGTERM_TEST_STOP:
pin_longterm_test_stop();
pin_longterm_test_stop(data);
ret = 0;
break;
case PIN_LONGTERM_TEST_READ:
ret = pin_longterm_test_read(arg);
ret = pin_longterm_test_read(data, arg);
break;
}
mutex_unlock(&pin_longterm_test_mutex);
mutex_unlock(&data->longterm_mutex);
return ret;
}
@ -375,15 +380,40 @@ static long gup_test_ioctl(struct file *filep, unsigned int cmd,
return 0;
}
static int gup_test_open(struct inode *inode, struct file *file)
{
struct gup_test_data *data;
int ret;
data = kzalloc_obj(*data);
if (!data)
return -ENOMEM;
ret = nonseekable_open(inode, file);
if (ret) {
kfree(data);
return ret;
}
mutex_init(&data->longterm_mutex);
file->private_data = data;
return 0;
}
static int gup_test_release(struct inode *inode, struct file *file)
{
pin_longterm_test_stop();
struct gup_test_data *data = file->private_data;
pin_longterm_test_stop(data);
mutex_destroy(&data->longterm_mutex);
kfree(data);
file->private_data = NULL;
return 0;
}
static const struct file_operations gup_test_fops = {
.open = nonseekable_open,
.open = gup_test_open,
.unlocked_ioctl = gup_test_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.release = gup_test_release,