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authorAl Viro <viro@zeniv.linux.org.uk>2017-11-19 11:21:10 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2017-12-02 20:29:12 -0500
commit14cb138d7c1c749d81dc3e66cd70f7a884e1da56 (patch)
tree6887b6c7763967fae4ddd7f0f305e8799366af45
parent9a949e8ff92246c0753b2805c2a001cb991fffe5 (diff)
downloadlinux-14cb138d7c1c749d81dc3e66cd70f7a884e1da56.tar.bz2
get_user_pages_unlocked(): pass true to __get_user_pages_locked() notify_drop
Equivalent transformation - the only place in __get_user_pages_locked() where we look at notify_drop argument is if (notify_drop && lock_dropped && *locked) { up_read(&mm->mmap_sem); *locked = 0; } in the very end. Changing notify_drop from false to true won't change behaviour unless *locked is non-zero. The caller is ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL, &locked, false, gup_flags | FOLL_TOUCH); if (locked) up_read(&mm->mmap_sem); so in that case the original kernel would have done up_read() right after return from __get_user_pages_locked(), while the modified one would've done it right before the return. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--mm/gup.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/gup.c b/mm/gup.c
index e7b9f5e97479..9418cbb3b1ad 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -988,7 +988,7 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
down_read(&mm->mmap_sem);
ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
- &locked, false, gup_flags | FOLL_TOUCH);
+ &locked, true, gup_flags | FOLL_TOUCH);
if (locked)
up_read(&mm->mmap_sem);
return ret;