From 0fd71a56f41d4ffabeda1dae9ff5ed4f34d4e935 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Wed, 11 Feb 2015 15:27:20 -0800 Subject: [PATCH] mm: gup: add __get_user_pages_unlocked to customize gup_flags Some callers (like KVM) may want to set the gup_flags like FOLL_HWPOSION to get a proper -EHWPOSION retval instead of -EFAULT to take a more appropriate action if get_user_pages runs into a memory failure. Signed-off-by: Andrea Arcangeli Reviewed-by: Kirill A. Shutemov Cc: Andres Lagar-Cavilla Cc: Peter Feiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 4 ++++ mm/gup.c | 44 ++++++++++++++++++++++++++++++++------------ mm/nommu.c | 16 +++++++++++++--- 3 files changed, 49 insertions(+), 15 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index fc499e6..3696b3b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1265,6 +1265,10 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, int *locked); +long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + unsigned int gup_flags); long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages); diff --git a/mm/gup.c b/mm/gup.c index 71a3773..dad5875 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -582,9 +582,9 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, int write, int force, struct page **pages, struct vm_area_struct **vmas, - int *locked, bool notify_drop) + int *locked, bool notify_drop, + unsigned int flags) { - int flags = FOLL_TOUCH; long ret, pages_done; bool lock_dropped; @@ -698,11 +698,37 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, int *locked) { return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, - pages, NULL, locked, true); + pages, NULL, locked, true, FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages_locked); /* + * Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows to + * pass additional gup_flags as last parameter (like FOLL_HWPOISON). + * + * NOTE: here FOLL_TOUCH is not set implicitly and must be set by the + * caller if required (just like with __get_user_pages). "FOLL_GET", + * "FOLL_WRITE" and "FOLL_FORCE" are set implicitly as needed + * according to the parameters "pages", "write", "force" + * respectively. + */ +__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + unsigned int gup_flags) +{ + long ret; + int locked = 1; + down_read(&mm->mmap_sem); + ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, + pages, NULL, &locked, false, gup_flags); + if (locked) + up_read(&mm->mmap_sem); + return ret; +} +EXPORT_SYMBOL(__get_user_pages_unlocked); + +/* * get_user_pages_unlocked() is suitable to replace the form: * * down_read(&mm->mmap_sem); @@ -723,14 +749,8 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) { - long ret; - int locked = 1; - down_read(&mm->mmap_sem); - ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, - pages, NULL, &locked, false); - if (locked) - up_read(&mm->mmap_sem); - return ret; + return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write, + force, pages, FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages_unlocked); @@ -794,7 +814,7 @@ long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, int force, struct page **pages, struct vm_area_struct **vmas) { return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, - pages, vmas, NULL, false); + pages, vmas, NULL, false, FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages); diff --git a/mm/nommu.c b/mm/nommu.c index bfb690b0..4d1b8a1 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -224,9 +224,10 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, } EXPORT_SYMBOL(get_user_pages_locked); -long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages) +long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + unsigned int gup_flags) { long ret; down_read(&mm->mmap_sem); @@ -235,6 +236,15 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, up_read(&mm->mmap_sem); return ret; } +EXPORT_SYMBOL(__get_user_pages_unlocked); + +long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages) +{ + return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write, + force, pages, 0); +} EXPORT_SYMBOL(get_user_pages_unlocked); /** -- 2.7.4