+ mm-gup_test-keep-longterm-pin-state-per-file.patch added to mm-new branch

+ mm-gup_test-keep-longterm-pin-state-per-file.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/gup_test: keep longterm pin state per file
has been added to the -mm mm-new branch.  Its filename is
     mm-gup_test-keep-longterm-pin-state-per-file.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup_test-keep-longterm-pin-state-per-file.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: "David Hildenbrand (Arm)" <david@kernel.org>
Subject: mm/gup_test: keep longterm pin state per file
Date: Mon, 10 Aug 2026 13:31:14 +0200

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: c77369b437f9 ("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>
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>
---

 mm/gup_test.c |   94 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 62 insertions(+), 32 deletions(-)

--- a/mm/gup_test.c~mm-gup_test-keep-longterm-pin-state-per-file
+++ a/mm/gup_test.c
@@ -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 @@ free_pages:
 	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_star
 	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_star
 		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_star
 			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_star
 	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
 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 *
 	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,
_

Patches currently in -mm which might be from david@kernel.org are

mm-standardize-printing-for-pgtable-entries.patch
mm-gup-fix-always-draining-lru-caches-in-collect_longterm_unpinnable_folios.patch
mm-gup-factor-out-lru-cache-draining-for-folio-into-lru_cache_drain_for_folio.patch
mm-gup_test-keep-longterm-pin-state-per-file.patch