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author | 2022-11-16 16:07:09 -0400 | |
---|---|---|
committer | 2022-11-30 15:58:56 -0800 | |
commit | 53b2d09bdd12092a7341c08b6b863560db62fa57 (patch) | |
tree | 99b1713aee05212084a2807c406c8c70b51cd322 /mm | |
parent | selftests/damon: fix unnecessary compilation warnings (diff) | |
download | linux-53b2d09bdd12092a7341c08b6b863560db62fa57.tar.gz linux-53b2d09bdd12092a7341c08b6b863560db62fa57.tar.bz2 linux-53b2d09bdd12092a7341c08b6b863560db62fa57.zip |
mm/gup: remove the restriction on locked with FOLL_LONGTERM
This restriction was created because FOLL_LONGTERM used to scan the vma
list, so it could not tolerate becoming unlocked. That was fixed in
commit 52650c8b466b ("mm/gup: remove the vma allocation from
gup_longterm_locked()") and the restriction on !vma was removed.
However, the locked restriction remained, even though it isn't necessary
anymore.
Adjust __gup_longterm_locked() so it can handle the mmap_read_lock()
becoming unlocked while it is looping for migration. Migration does not
require the mmap_read_sem because it is only handling struct pages. If we
had to unlock then ensure the whole thing returns unlocked.
Remove __get_user_pages_remote() and __gup_longterm_unlocked(). These
cases can now just directly call other functions.
Link: https://lkml.kernel.org/r/0-v1-b9ae39aa8884+14dbb-gup_longterm_locked_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/gup.c | 109 |
1 files changed, 27 insertions, 82 deletions
@@ -2049,14 +2049,19 @@ static long __gup_longterm_locked(struct mm_struct *mm, unsigned long nr_pages, struct page **pages, struct vm_area_struct **vmas, + int *locked, unsigned int gup_flags) { + bool must_unlock = false; unsigned int flags; long rc, nr_pinned_pages; + if (locked && WARN_ON_ONCE(!*locked)) + return -EINVAL; + if (!(gup_flags & FOLL_LONGTERM)) return __get_user_pages_locked(mm, start, nr_pages, pages, vmas, - NULL, gup_flags); + locked, gup_flags); /* * If we get to this point then FOLL_LONGTERM is set, and FOLL_LONGTERM @@ -2070,8 +2075,13 @@ static long __gup_longterm_locked(struct mm_struct *mm, return -EINVAL; flags = memalloc_pin_save(); do { + if (locked && !*locked) { + mmap_read_lock(mm); + must_unlock = true; + *locked = 1; + } nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages, - pages, vmas, NULL, + pages, vmas, locked, gup_flags); if (nr_pinned_pages <= 0) { rc = nr_pinned_pages; @@ -2081,6 +2091,10 @@ static long __gup_longterm_locked(struct mm_struct *mm, } while (rc == -EAGAIN); memalloc_pin_restore(flags); + if (locked && *locked && must_unlock) { + mmap_read_unlock(mm); + *locked = 0; + } return rc ? rc : nr_pinned_pages; } @@ -2104,35 +2118,6 @@ static bool is_valid_gup_flags(unsigned int gup_flags) } #ifdef CONFIG_MMU -static long __get_user_pages_remote(struct mm_struct *mm, - unsigned long start, unsigned long nr_pages, - unsigned int gup_flags, struct page **pages, - struct vm_area_struct **vmas, int *locked) -{ - /* - * Parts of FOLL_LONGTERM behavior are incompatible with - * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on - * vmas. However, this only comes up if locked is set, and there are - * callers that do request FOLL_LONGTERM, but do not set locked. So, - * allow what we can. - */ - if (gup_flags & FOLL_LONGTERM) { - 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, - vmas, gup_flags | FOLL_TOUCH | - FOLL_REMOTE); - } - - return __get_user_pages_locked(mm, start, nr_pages, pages, vmas, - locked, - gup_flags | FOLL_TOUCH | FOLL_REMOTE); -} - /** * get_user_pages_remote() - pin user pages in memory * @mm: mm_struct of target mm @@ -2201,8 +2186,8 @@ long get_user_pages_remote(struct mm_struct *mm, if (!is_valid_gup_flags(gup_flags)) return -EINVAL; - return __get_user_pages_remote(mm, start, nr_pages, gup_flags, - pages, vmas, locked); + return __gup_longterm_locked(mm, start, nr_pages, pages, vmas, locked, + gup_flags | FOLL_TOUCH | FOLL_REMOTE); } EXPORT_SYMBOL(get_user_pages_remote); @@ -2214,14 +2199,6 @@ long get_user_pages_remote(struct mm_struct *mm, { return 0; } - -static long __get_user_pages_remote(struct mm_struct *mm, - unsigned long start, unsigned long nr_pages, - unsigned int gup_flags, struct page **pages, - struct vm_area_struct **vmas, int *locked) -{ - return 0; -} #endif /* !CONFIG_MMU */ /** @@ -2248,7 +2225,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, return -EINVAL; return __gup_longterm_locked(current->mm, start, nr_pages, - pages, vmas, gup_flags | FOLL_TOUCH); + pages, vmas, NULL, gup_flags | FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages); @@ -2274,18 +2251,9 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int locked = 1; long ret; - /* - * FIXME: Current FOLL_LONGTERM behavior is incompatible with - * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on - * vmas. As there are no users of this flag in this call we simply - * disallow this option for now. - */ - if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM)) - return -EINVAL; - mmap_read_lock(mm); - ret = __get_user_pages_locked(mm, start, nr_pages, pages, NULL, - &locked, gup_flags | FOLL_TOUCH); + ret = __gup_longterm_locked(mm, start, nr_pages, pages, NULL, &locked, + gup_flags | FOLL_TOUCH); if (locked) mmap_read_unlock(mm); return ret; @@ -2879,29 +2847,6 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end) } #endif -static int __gup_longterm_unlocked(unsigned long start, int nr_pages, - unsigned int gup_flags, struct page **pages) -{ - int ret; - - /* - * FIXME: FOLL_LONGTERM does not work with - * get_user_pages_unlocked() (see comments in that function) - */ - if (gup_flags & FOLL_LONGTERM) { - mmap_read_lock(current->mm); - ret = __gup_longterm_locked(current->mm, - start, nr_pages, - pages, NULL, gup_flags); - mmap_read_unlock(current->mm); - } else { - ret = get_user_pages_unlocked(start, nr_pages, - pages, gup_flags); - } - - return ret; -} - static unsigned long lockless_pages_from_mm(unsigned long start, unsigned long end, unsigned int gup_flags, @@ -2985,8 +2930,8 @@ static int internal_get_user_pages_fast(unsigned long start, /* Slow path: try to get the remaining pages with get_user_pages */ start += nr_pinned << PAGE_SHIFT; pages += nr_pinned; - ret = __gup_longterm_unlocked(start, nr_pages - nr_pinned, gup_flags, - pages); + ret = get_user_pages_unlocked(start, nr_pages - nr_pinned, pages, + gup_flags); if (ret < 0) { /* * The caller has to unpin the pages we already pinned so @@ -3185,9 +3130,9 @@ long pin_user_pages_remote(struct mm_struct *mm, 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); + return __gup_longterm_locked(mm, start, nr_pages, pages, vmas, locked, + gup_flags | FOLL_PIN | FOLL_TOUCH | + FOLL_REMOTE); } EXPORT_SYMBOL(pin_user_pages_remote); @@ -3221,7 +3166,7 @@ long pin_user_pages(unsigned long start, unsigned long nr_pages, gup_flags |= FOLL_PIN; return __gup_longterm_locked(current->mm, start, nr_pages, - pages, vmas, gup_flags); + pages, vmas, NULL, gup_flags); } EXPORT_SYMBOL(pin_user_pages); |