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ANDROID: mm: retry GUP with orignal gup_flags on failure

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If GUP fails due to modified flags by vendor hook,
try one more time with original flag to keep the
API semantic.

Bug: 229391920
Signed-off-by: Minchan Kim <minchan@google.com>
Change-Id: If2c20fe3e1752c9cc0d7d350ad84b38d8325f9ae
This commit is contained in:
Minchan Kim
2022-04-15 09:30:21 -07:00
parent 6acb261444
commit d5d9a23576
1 changed files with 22 additions and 3 deletions
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25
mm/gup.c
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@@ -1740,6 +1740,8 @@ static long __get_user_pages_remote(struct mm_struct *mm,
unsigned int gup_flags, struct page **pages,
struct vm_area_struct **vmas, int *locked)
{
unsigned int orig_gup_flags = gup_flags;
trace_android_vh___get_user_pages_remote(locked, &gup_flags, pages);
/*
@@ -1749,16 +1751,23 @@ static long __get_user_pages_remote(struct mm_struct *mm,
* callers that do request FOLL_LONGTERM, but do not set locked. So,
* allow what we can.
*/
retry:
if (gup_flags & FOLL_LONGTERM) {
long ret;
if (WARN_ON_ONCE(locked))
return -EINVAL;
/*
* This will check the vmas (even if our vmas arg is NULL)
* and return -ENOTSUPP if DAX isn't allowed in this case:
*/
return __gup_longterm_locked(mm, start, nr_pages, pages,
ret = __gup_longterm_locked(mm, start, nr_pages, pages,
vmas, gup_flags | FOLL_TOUCH |
FOLL_REMOTE);
if (ret < 0 && orig_gup_flags != gup_flags) {
gup_flags = orig_gup_flags;
goto retry;
}
}
return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
@@ -1877,13 +1886,23 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
struct vm_area_struct **vmas)
{
long ret;
unsigned int orig_gup_flags;
if (!is_valid_gup_flags(gup_flags))
return -EINVAL;
orig_gup_flags = gup_flags;
trace_android_vh_get_user_pages(&gup_flags, pages);
return __gup_longterm_locked(current->mm, start, nr_pages,
retry:
ret = __gup_longterm_locked(current->mm, start, nr_pages,
pages, vmas, gup_flags | FOLL_TOUCH);
if (ret < 0 && orig_gup_flags != gup_flags) {
gup_flags = orig_gup_flags;
goto retry;
}
return ret;
}
EXPORT_SYMBOL(get_user_pages);