Messages in this thread Patch in this message | | | Date | Fri, 21 Nov 2008 17:31:49 -0800 | Subject | [PATCH][V3]Make get_user_pages interruptible | From | Ying Han <> |
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From: Paul Menage <menage@google.com>
make get_user_pages interruptible 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@google.com> Singed-off-by: Ying Han <yinghan@google.com>
include/linux/sched.h | 1 + kernel/signal.c | 2 +- mm/memory.c | 9 +-
diff --git a/include/linux/sched.h b/include/linux/sched.h index b483f39..f9c6a8a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1790,6 +1790,7 @@ extern void sched_dead(struct task_struct *p); extern int in_group_p(gid_t); extern int in_egroup_p(gid_t);
+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 --git a/kernel/signal.c b/kernel/signal.c index 105217d..f3f154e 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1497,7 +1497,7 @@ 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 --git a/mm/memory.c b/mm/memory.c index 164951c..ae24300 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1218,12 +1218,11 @@ int __get_user_pages(struct task_struct *tsk, struct m 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(tsk))) + return i ? i : -ERESTARTSYS;
if (write) foll_flags |= FOLL_WRITE;
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