The patch titled
Subject: mm/gup: might_lock_read(mmap_sem) in get_user_pages_fast()
has been added to the -mm tree. Its filename is
mm-gup-might_lock_readmmap_sem-in-get_user_pages_fast.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-might_lock_readmmap_sem-in-get_user_pages_fast.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-might_lock_readmmap_sem-in-get_user_pages_fast.patch
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------------------------------------------------------
From: John Hubbard <jhubbard@xxxxxxxxxx>
Subject: mm/gup: might_lock_read(mmap_sem) in get_user_pages_fast()
Instead of scattering these assertions across the drivers, do this
assertion inside the core of get_user_pages_fast*() functions. That also
includes pin_user_pages_fast*() routines.
Add a might_lock_read(mmap_sem) call to internal_get_user_pages_fast().
Link: http://lkml.kernel.org/r/20200522010443.1290485-1-jhubbard@xxxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 3 +++
1 file changed, 3 insertions(+)
--- a/mm/gup.c~mm-gup-might_lock_readmmap_sem-in-get_user_pages_fast
+++ a/mm/gup.c
@@ -2723,6 +2723,9 @@ static int internal_get_user_pages_fast(
FOLL_FAST_ONLY)))
return -EINVAL;
+ if (!(gup_flags & FOLL_FAST_ONLY))
+ might_lock_read(¤t->mm->mmap_sem);
+
start = untagged_addr(start) & PAGE_MASK;
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;
_
Patches currently in -mm which might be from jhubbard@xxxxxxxxxx are
rapidio-fix-an-error-in-get_user_pages_fast-error-handling.patch
selftests-vm-gitignore-add-mremap_dontunmap.patch
selftests-vm-write_to_hugetlbfsc-fix-unused-variable-warning.patch
mm-gup-introduce-pin_user_pages_unlocked.patch
ivtv-convert-get_user_pages-pin_user_pages.patch
mm-gup-move-__get_user_pages_fast-down-a-few-lines-in-gupc.patch
mm-gup-refactor-and-de-duplicate-gup_fast-code.patch
mm-gup-refactor-and-de-duplicate-gup_fast-code-fix.patch
mm-gup-introduce-pin_user_pages_fast_only.patch
drm-i915-convert-get_user_pages-pin_user_pages.patch
mm-gup-might_lock_readmmap_sem-in-get_user_pages_fast.patch
khugepaged-add-self-test-fix-3.patch
rapidio-convert-get_user_pages-pin_user_pages.patch
