mm/gup_test: start/stop/read functionality for PIN LONGTERM test

We want an easy way to take a R/O or R/W longterm pin on a range and be
able to observe the content of the pinned pages, so we can properly test
how longterm puns interact with our COW logic.

[david@redhat.com: silence a warning on 32-bit]
Link: https://lkml.kernel.org/r/74adbb51-6e33-f636-8a9c-2ad87bd9007e@redhat.com
[yang.lee@linux.alibaba.com: ./mm/gup_test.c:281:2-3: Unneeded semicolon]
Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2455
Link: https://lkml.kernel.org/r/20221020024035.113619-1-yang.lee@linux.alibaba.com
Link: https://lkml.kernel.org/r/20220927110120.106906-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph von Recklinghausen <crecklin@redhat.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/gup_test.c b/mm/gup_test.c
index 12b0a91..0d76d9b 100644 (file)
--- a/mm/gup_test.c
+++ b/mm/gup_test.c
@@ -203,6 +203,135 @@ 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)
+{
+       if (pin_longterm_test_pages) {
+               if (pin_longterm_test_nr_pages)
+                       unpin_user_pages(pin_longterm_test_pages,
+                                        pin_longterm_test_nr_pages);
+               kfree(pin_longterm_test_pages);
+               pin_longterm_test_pages = NULL;
+               pin_longterm_test_nr_pages = 0;
+       }
+}
+
+static inline int pin_longterm_test_start(unsigned long arg)
+{
+       long nr_pages, cur_pages, addr, remaining_pages;
+       int gup_flags = FOLL_LONGTERM;
+       struct pin_longterm_test args;
+       struct page **pages;
+       int ret = 0;
+       bool fast;
+
+       if (pin_longterm_test_pages)
+               return -EINVAL;
+
+       if (copy_from_user(&args, (void __user *)arg, sizeof(args)))
+               return -EFAULT;
+
+       if (args.flags &
+           ~(PIN_LONGTERM_TEST_FLAG_USE_WRITE|PIN_LONGTERM_TEST_FLAG_USE_FAST))
+               return -EINVAL;
+       if (!IS_ALIGNED(args.addr | args.size, PAGE_SIZE))
+               return -EINVAL;
+       if (args.size > LONG_MAX)
+               return -EINVAL;
+       nr_pages = args.size / PAGE_SIZE;
+       if (!nr_pages)
+               return -EINVAL;
+
+       pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);
+       if (!pages)
+               return -ENOMEM;
+
+       if (args.flags & PIN_LONGTERM_TEST_FLAG_USE_WRITE)
+               gup_flags |= FOLL_WRITE;
+       fast = !!(args.flags & PIN_LONGTERM_TEST_FLAG_USE_FAST);
+
+       if (!fast && mmap_read_lock_killable(current->mm)) {
+               kfree(pages);
+               return -EINTR;
+       }
+
+       pin_longterm_test_pages = pages;
+       pin_longterm_test_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;
+
+               if (fast)
+                       cur_pages = pin_user_pages_fast(addr, remaining_pages,
+                                                       gup_flags, pages);
+               else
+                       cur_pages = pin_user_pages(addr, remaining_pages,
+                                                  gup_flags, pages, NULL);
+               if (cur_pages < 0) {
+                       pin_longterm_test_stop();
+                       ret = cur_pages;
+                       break;
+               }
+               pin_longterm_test_nr_pages += cur_pages;
+               pages += cur_pages;
+       }
+
+       if (!fast)
+               mmap_read_unlock(current->mm);
+       return ret;
+}
+
+static inline int pin_longterm_test_read(unsigned long arg)
+{
+       __u64 user_addr;
+       unsigned long i;
+
+       if (!pin_longterm_test_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 = page_to_virt(pin_longterm_test_pages[i]);
+
+               if (copy_to_user((void __user *)(unsigned long)user_addr, addr,
+                                PAGE_SIZE))
+                       return -EFAULT;
+               user_addr += PAGE_SIZE;
+       }
+       return 0;
+}
+
+static long pin_longterm_test_ioctl(struct file *filep, unsigned int cmd,
+                                   unsigned long arg)
+{
+       int ret = -EINVAL;
+
+       if (mutex_lock_killable(&pin_longterm_test_mutex))
+               return -EINTR;
+
+       switch (cmd) {
+       case PIN_LONGTERM_TEST_START:
+               ret = pin_longterm_test_start(arg);
+               break;
+       case PIN_LONGTERM_TEST_STOP:
+               pin_longterm_test_stop();
+               ret = 0;
+               break;
+       case PIN_LONGTERM_TEST_READ:
+               ret = pin_longterm_test_read(arg);
+               break;
+       }
+
+       mutex_unlock(&pin_longterm_test_mutex);
+       return ret;
+}
+
 static long gup_test_ioctl(struct file *filep, unsigned int cmd,
                unsigned long arg)
 {
@@ -217,6 +346,10 @@ static long gup_test_ioctl(struct file *filep, unsigned int cmd,
        case PIN_BASIC_TEST:
        case DUMP_USER_PAGES_TEST:
                break;
+       case PIN_LONGTERM_TEST_START:
+       case PIN_LONGTERM_TEST_STOP:
+       case PIN_LONGTERM_TEST_READ:
+               return pin_longterm_test_ioctl(filep, cmd, arg);
        default:
                return -EINVAL;
        }
@@ -234,9 +367,17 @@ static long gup_test_ioctl(struct file *filep, unsigned int cmd,
        return 0;
 }
 
+static int gup_test_release(struct inode *inode, struct file *file)
+{
+       pin_longterm_test_stop();
+
+       return 0;
+}
+
 static const struct file_operations gup_test_fops = {
        .open = nonseekable_open,
        .unlocked_ioctl = gup_test_ioctl,
+       .release = gup_test_release,
 };
 
 static int __init gup_test_init(void)

diff --git a/mm/gup_test.h b/mm/gup_test.h
index 887ac1d..5b37b54 100644 (file)
--- a/mm/gup_test.h
+++ b/mm/gup_test.h
@@ -10,6 +10,9 @@
 #define GUP_BASIC_TEST         _IOWR('g', 4, struct gup_test)
 #define PIN_BASIC_TEST         _IOWR('g', 5, struct gup_test)
 #define DUMP_USER_PAGES_TEST   _IOWR('g', 6, struct gup_test)
+#define PIN_LONGTERM_TEST_START        _IOW('g', 7, struct pin_longterm_test)
+#define PIN_LONGTERM_TEST_STOP _IO('g', 8)
+#define PIN_LONGTERM_TEST_READ _IOW('g', 9, __u64)
 
 #define GUP_TEST_MAX_PAGES_TO_DUMP             8
 
@@ -30,4 +33,13 @@ struct gup_test {
        __u32 which_pages[GUP_TEST_MAX_PAGES_TO_DUMP];
 };
 
+#define PIN_LONGTERM_TEST_FLAG_USE_WRITE       1
+#define PIN_LONGTERM_TEST_FLAG_USE_FAST                2
+
+struct pin_longterm_test {
+       __u64 addr;
+       __u64 size;
+       __u32 flags;
+};
+
 #endif /* __GUP_TEST_H */