The patch titled
Subject: mm/gup: fix comments to pin_user_pages_*()
has been added to the -mm tree. Its filename is
mm-gup-fix-comments-to-pin_user_pages_.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-gup-fix-comments-to-pin_user_pages_.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-fix-comments-to-pin_user_pages_.patch
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------------------------------------------------------
From: Yury Norov <yury.norov@xxxxxxxxx>
Subject: mm/gup: fix comments to pin_user_pages_*()
pin_user_pages API forces FOLL_PIN in gup_flags, which means that the API
requires struct page **pages to be provided (not NULL). However, the
comment to pin_user_pages() clearly allows for passing in a NULL @pages
argument.
Remove the incorrect comments, and add WARN_ON_ONCE(!pages) calls to
enforce the API.
It has been independently spotted by Minchan Kim and confirmed with
John Hubbard:
https://lore.kernel.org/all/YgWA0ghrrzHONehH@xxxxxxxxxx/
Link: https://lkml.kernel.org/r/20220422015839.1274328-1-yury.norov@xxxxxxxxx
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@xxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
--- a/mm/gup.c~mm-gup-fix-comments-to-pin_user_pages_
+++ a/mm/gup.c
@@ -2969,6 +2969,9 @@ int pin_user_pages_fast(unsigned long st
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
return -EINVAL;
+ if (WARN_ON_ONCE(!pages))
+ return -EINVAL;
+
gup_flags |= FOLL_PIN;
return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
}
@@ -2991,6 +2994,9 @@ int pin_user_pages_fast_only(unsigned lo
*/
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
return 0;
+
+ if (WARN_ON_ONCE(!pages))
+ return 0;
/*
* FOLL_FAST_ONLY is required in order to match the API description of
* this routine: no fall back to regular ("slow") GUP.
@@ -3018,8 +3024,7 @@ EXPORT_SYMBOL_GPL(pin_user_pages_fast_on
* @nr_pages: number of pages from start to pin
* @gup_flags: flags modifying lookup behaviour
* @pages: array that receives pointers to the pages pinned.
- * Should be at least nr_pages long. Or NULL, if caller
- * only intends to ensure the pages are faulted in.
+ * Should be at least nr_pages long.
* @vmas: array of pointers to vmas corresponding to each page.
* Or NULL if the caller does not require them.
* @locked: pointer to lock flag indicating whether lock is held and
@@ -3042,6 +3047,9 @@ long pin_user_pages_remote(struct mm_str
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
return -EINVAL;
+ if (WARN_ON_ONCE(!pages))
+ return -EINVAL;
+
gup_flags |= FOLL_PIN;
return __get_user_pages_remote(mm, start, nr_pages, gup_flags,
pages, vmas, locked);
@@ -3055,8 +3063,7 @@ EXPORT_SYMBOL(pin_user_pages_remote);
* @nr_pages: number of pages from start to pin
* @gup_flags: flags modifying lookup behaviour
* @pages: array that receives pointers to the pages pinned.
- * Should be at least nr_pages long. Or NULL, if caller
- * only intends to ensure the pages are faulted in.
+ * Should be at least nr_pages long.
* @vmas: array of pointers to vmas corresponding to each page.
* Or NULL if the caller does not require them.
*
@@ -3074,6 +3081,9 @@ long pin_user_pages(unsigned long start,
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
return -EINVAL;
+ if (WARN_ON_ONCE(!pages))
+ return -EINVAL;
+
gup_flags |= FOLL_PIN;
return __gup_longterm_locked(current->mm, start, nr_pages,
pages, vmas, gup_flags);
@@ -3092,6 +3102,9 @@ long pin_user_pages_unlocked(unsigned lo
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
return -EINVAL;
+ if (WARN_ON_ONCE(!pages))
+ return -EINVAL;
+
gup_flags |= FOLL_PIN;
return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
}
_
Patches currently in -mm which might be from yury.norov@xxxxxxxxx are
mm-gup-fix-comments-to-pin_user_pages_.patch
