The patch titled
mm: make get_user_pages interruptible
has been added to the -mm tree. Its filename is
make-get_user_pages-interruptible.patch
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------------------------------------------------------
Subject: mm: make get_user_pages interruptible
From: Ying Han <yinghan@xxxxxxxxxx>
The initial implementation of checking TIF_MEMDIE covers the cases of OOM
killing. If the process has been OOM killed, the TIF_MEMDIE is set and it
return immediately. This patch includes:
1. add the case that the SIGKILL is sent by user processes. The
process can try to get_user_pages() unlimited memory even if a user
process has sent a SIGKILL to it(maybe a monitor find the process
exceed its memory limit and try to kill it). In the old
implementation, the SIGKILL won't be handled until the get_user_pages()
returns.
2. change the return value to be ERESTARTSYS. It makes no sense to
return ENOMEM if the get_user_pages returned by getting a SIGKILL
signal. Considering the general convention for a system call
interrupted by a signal is ERESTARTNOSYS, so the current return value
is consistant to that.
Signed-off-by: Paul Menage <menage@xxxxxxxxxx>
Signed-off-by:Ying Han <yinghan@xxxxxxxxxx>
Acked-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Matthew Wilcox <matthew@xxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 1 +
kernel/signal.c | 2 +-
mm/memory.c | 10 +++++-----
3 files changed, 7 insertions(+), 6 deletions(-)
diff -puN include/linux/sched.h~make-get_user_pages-interruptible include/linux/sched.h
--- a/include/linux/sched.h~make-get_user_pages-interruptible
+++ a/include/linux/sched.h
@@ -1750,6 +1750,7 @@ extern void wake_up_new_task(struct task
extern void sched_fork(struct task_struct *p, int clone_flags);
extern void sched_dead(struct task_struct *p);
+extern int sigkill_pending(struct task_struct *tsk);
extern void proc_caches_init(void);
extern void flush_signals(struct task_struct *);
extern void ignore_signals(struct task_struct *);
diff -puN kernel/signal.c~make-get_user_pages-interruptible kernel/signal.c
--- a/kernel/signal.c~make-get_user_pages-interruptible
+++ a/kernel/signal.c
@@ -1516,7 +1516,7 @@ static inline int may_ptrace_stop(void)
* Return nonzero if there is a SIGKILL that should be waking us up.
* Called with the siglock held.
*/
-static int sigkill_pending(struct task_struct *tsk)
+int sigkill_pending(struct task_struct *tsk)
{
return sigismember(&tsk->pending.signal, SIGKILL) ||
sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
diff -puN mm/memory.c~make-get_user_pages-interruptible mm/memory.c
--- a/mm/memory.c~make-get_user_pages-interruptible
+++ a/mm/memory.c
@@ -1219,12 +1219,12 @@ int __get_user_pages(struct task_struct
struct page *page;
/*
- * If tsk is ooming, cut off its access to large memory
- * allocations. It has a pending SIGKILL, but it can't
- * be processed until returning to user space.
+ * If we have a pending SIGKILL, don't keep
+ * allocating memory.
*/
- if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
- return i ? i : -ENOMEM;
+ if (unlikely(sigkill_pending(current) ||
+ sigkill_pending(tsk)))
+ return i ? i : -ERESTARTSYS;
if (write)
foll_flags |= FOLL_WRITE;
_
Patches currently in -mm which might be from yinghan@xxxxxxxxxx are
make-get_user_pages-interruptible.patch
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