From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm: make vm_brk killable
Now that all the callers handle vm_brk failure we can change it wait for
mmap_sem killable to help oom_reaper to not get blocked just because
vm_brk gets blocked behind mmap_sem readers.
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 2 +-
mm/mmap.c | 9 +++------
2 files changed, 4 insertions(+), 7 deletions(-)
diff -puN include/linux/mm.h~mm-make-vm_brk-killable include/linux/mm.h
--- a/include/linux/mm.h~mm-make-vm_brk-killable
+++ a/include/linux/mm.h
@@ -2011,7 +2011,7 @@ static inline void mm_populate(unsigned
#endif
/* These take the mm semaphore themselves */
-extern unsigned long vm_brk(unsigned long, unsigned long);
+extern unsigned long __must_check vm_brk(unsigned long, unsigned long);
extern int vm_munmap(unsigned long, size_t);
extern unsigned long __must_check vm_mmap(struct file *, unsigned long,
unsigned long, unsigned long,
diff -puN mm/mmap.c~mm-make-vm_brk-killable mm/mmap.c
--- a/mm/mmap.c~mm-make-vm_brk-killable
+++ a/mm/mmap.c
@@ -2712,12 +2712,9 @@ unsigned long vm_brk(unsigned long addr,
unsigned long ret;
bool populate;
- /*
- * XXX not all users are chcecking the return value, convert
- * to down_write_killable after they are able to cope with
- * error
- */
- down_write(&mm->mmap_sem);
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
ret = do_brk(addr, len);
populate = ((mm->def_flags & VM_LOCKED) != 0);
up_write(&mm->mmap_sem);
_
--
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