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mm: add locked parameter to get_user_pages_remote()

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Patch series "mm: unexport __get_user_pages_unlocked()".

This patch series continues the cleanup of get_user_pages*() functions
taking advantage of the fact we can now pass gup_flags as we please.

It firstly adds an additional 'locked' parameter to
get_user_pages_remote() to allow for its callers to utilise
VM_FAULT_RETRY functionality.  This is necessary as the invocation of
__get_user_pages_unlocked() in process_vm_rw_single_vec() makes use of
this and no other existing higher level function would allow it to do
so.

Secondly existing callers of __get_user_pages_unlocked() are replaced
with the appropriate higher-level replacement -
get_user_pages_unlocked() if the current task and memory descriptor are
referenced, or get_user_pages_remote() if other task/memory descriptors
are referenced (having acquiring mmap_sem.)

This patch (of 2):

Add a int *locked parameter to get_user_pages_remote() to allow
VM_FAULT_RETRY faulting behaviour similar to get_user_pages_[un]locked().

Taking into account the previous adjustments to get_user_pages*()
functions allowing for the passing of gup_flags, we are now in a
position where __get_user_pages_unlocked() need only be exported for his
ability to allow VM_FAULT_RETRY behaviour, this adjustment allows us to
subsequently unexport __get_user_pages_unlocked() as well as allowing
for future flexibility in the use of get_user_pages_remote().

[[email protected]: merge fix for get_user_pages_remote API change]
  Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Lorenzo Stoakes <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Radim Krcmar <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Lorenzo Stoakes 2016-12-14 15:06:52 -08:00 • committed by Linus Torvalds
commit 5b56d49fc3
10 changed files with 18 additions and 14 deletions
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12
mm/gup.c
View file

@ -917,6 +917,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
* only intends to ensure the pages are faulted in.
* @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
* subsequently whether VM_FAULT_RETRY functionality can be
* utilised. Lock must initially be held.
*
* Returns number of pages pinned. This may be fewer than the number
* requested. If nr_pages is 0 or negative, returns 0. If no pages
@ -960,10 +963,10 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
struct vm_area_struct **vmas)
struct vm_area_struct **vmas, int *locked)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
NULL, false,
locked, true,
gup_flags | FOLL_TOUCH | FOLL_REMOTE);
}
EXPORT_SYMBOL(get_user_pages_remote);
@ -971,8 +974,9 @@ EXPORT_SYMBOL(get_user_pages_remote);
/*
* This is the same as get_user_pages_remote(), just with a
* less-flexible calling convention where we assume that the task
* and mm being operated on are the current task's. We also
* obviously don't pass FOLL_REMOTE in here.
* and mm being operated on are the current task's and don't allow
* passing of a locked parameter. We also obviously don't pass
* FOLL_REMOTE in here.
*/
long get_user_pages(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,