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From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	linux-api@vger.kernel.org, oleksandr@redhat.com,
	Suren Baghdasaryan <surenb@google.com>,
	Tim Murray <timmurray@google.com>,
	Daniel Colascione <dancol@google.com>,
	Sandeep Patil <sspatil@google.com>,
	Sonny Rao <sonnyrao@google.com>,
	Brian Geffon <bgeffon@google.com>, Michal Hocko <mhocko@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>,
	John Dias <joaodias@google.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Jann Horn <jannh@google.com>,
	alexander.h.duyck@linux.intel.com, sj38.park@gmail.com,
	Minchan Kim <minchan@kernel.org>,
	Christian Brauner <christian@brauner.io>,
	Kirill Tkhai <ktkhai@virtuozzo.com>
Subject: [PATCH v7 5/7] mm: support both pid and pidfd for process_madvise
Date: Mon,  2 Mar 2020 11:36:28 -0800	[thread overview]
Message-ID: <20200302193630.68771-6-minchan@kernel.org> (raw)
In-Reply-To: <20200302193630.68771-1-minchan@kernel.org>

There is a demand[1] to support pid as well pidfd for process_madvise
to reduce unnecessary syscall to get pidfd if the user has control of
the target process(ie, they could guarantee the process is not gone
or pid is not reused).

This patch aims for supporting both options like waitid(2). So, the
syscall is currently,

	int process_madvise(int which, pid_t pid, void *addr,
		size_t length, int advise, unsigned long flag);

@which is actually idtype_t for userspace libray and currently,
it supports P_PID and P_PIDFD.

[1]  https://lore.kernel.org/linux-mm/9d849087-3359-c4ab-fbec-859e8186c509@virtuozzo.com/

Cc: Christian Brauner <christian@brauner.io>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/syscalls.h |  3 ++-
 mm/madvise.c             | 34 ++++++++++++++++++++++------------
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index e4cd2c2f8bb4..f5ada20e2943 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -876,7 +876,8 @@ asmlinkage long sys_munlockall(void);
 asmlinkage long sys_mincore(unsigned long start, size_t len,
 				unsigned char __user * vec);
 asmlinkage long sys_madvise(unsigned long start, size_t len, int behavior);
-asmlinkage long sys_process_madvise(int pidfd, unsigned long start,
+
+asmlinkage long sys_process_madvise(int which, pid_t pid, unsigned long start,
 			size_t len, int behavior, unsigned long flags);
 asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
 			unsigned long prot, unsigned long pgoff,
diff --git a/mm/madvise.c b/mm/madvise.c
index 6543f2bfc3d8..e794367f681e 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1182,11 +1182,10 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
 	return do_madvise(current, current->mm, start, len_in, behavior);
 }
 
-SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start,
+SYSCALL_DEFINE6(process_madvise, int, which, pid_t, upid, unsigned long, start,
 		size_t, len_in, int, behavior, unsigned long, flags)
 {
 	int ret;
-	struct fd f;
 	struct pid *pid;
 	struct task_struct *task;
 	struct mm_struct *mm;
@@ -1197,20 +1196,31 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start,
 	if (!process_madvise_behavior_valid(behavior))
 		return -EINVAL;
 
-	f = fdget(pidfd);
-	if (!f.file)
-		return -EBADF;
+	switch (which) {
+	case P_PID:
+		if (upid <= 0)
+			return -EINVAL;
+
+		pid = find_get_pid(upid);
+		if (!pid)
+			return -ESRCH;
+		break;
+	case P_PIDFD:
+		if (upid < 0)
+			return -EINVAL;
 
-	pid = pidfd_pid(f.file);
-	if (IS_ERR(pid)) {
-		ret = PTR_ERR(pid);
-		goto fdput;
+		pid = pidfd_get_pid(upid);
+		if (IS_ERR(pid))
+			return PTR_ERR(pid);
+		break;
+	default:
+		return -EINVAL;
 	}
 
 	task = get_pid_task(pid, PIDTYPE_PID);
 	if (!task) {
 		ret = -ESRCH;
-		goto fdput;
+		goto put_pid;
 	}
 
 	mm = mm_access(task, PTRACE_MODE_ATTACH_FSCREDS);
@@ -1223,7 +1233,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start,
 	mmput(mm);
 release_task:
 	put_task_struct(task);
-fdput:
-	fdput(f);
+put_pid:
+	put_pid(pid);
 	return ret;
 }
-- 
2.25.0.265.gbab2e86ba0-goog



  parent reply	other threads:[~2020-03-02 19:36 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-02 19:36 [PATCH v7 0/7] introduce memory hinting API for external process Minchan Kim
2020-03-02 19:36 ` [PATCH v7 1/7] mm: pass task and mm to do_madvise Minchan Kim
2020-03-05 15:48   ` Vlastimil Babka
2020-05-08 18:21     ` Minchan Kim
2020-03-02 19:36 ` [PATCH v7 2/7] mm: introduce external memory hinting API Minchan Kim
2020-03-03 10:33   ` kbuild test robot
2020-03-03 14:57     ` Minchan Kim
2020-03-05 18:15   ` Vlastimil Babka
2020-03-10 22:20     ` Minchan Kim
2020-03-11  0:36       ` Minchan Kim
2020-03-12 12:40       ` Vlastimil Babka
2020-03-12 20:23         ` Minchan Kim
2020-05-08 18:33           ` Minchan Kim
2020-03-02 19:36 ` [PATCH v7 3/7] mm: check fatal signal pending of target process Minchan Kim
2020-03-06 10:22   ` Vlastimil Babka
2020-03-10 22:24     ` Minchan Kim
2020-03-02 19:36 ` [PATCH v7 4/7] pid: move pidfd_get_pid function to pid.c Minchan Kim
2020-03-06 10:57   ` Vlastimil Babka
2020-03-06 11:14   ` Christian Brauner
2020-03-02 19:36 ` Minchan Kim [this message]
2020-03-06 11:14   ` [PATCH v7 5/7] mm: support both pid and pidfd for process_madvise Vlastimil Babka
2020-03-11  0:42     ` Minchan Kim
2020-05-08 18:36       ` Minchan Kim
2020-05-08 23:04         ` Andrew Morton
2020-05-09 12:48           ` Christian Brauner
2020-05-09 23:14             ` Minchan Kim
2020-05-12 19:55               ` Suren Baghdasaryan
2020-03-02 19:36 ` [PATCH v7 6/7] mm/madvise: employ mmget_still_valid for write lock Minchan Kim
2020-03-06 12:52   ` Vlastimil Babka
2020-03-06 13:03     ` Oleksandr Natalenko
2020-03-06 16:03       ` Vlastimil Babka
2020-03-09 12:30         ` Oleksandr Natalenko
2020-03-10 22:28           ` Minchan Kim
2020-03-02 19:36 ` [PATCH v7 7/7] mm/madvise: allow KSM hints for remote API Minchan Kim
2020-03-06 13:13   ` Vlastimil Babka
2020-03-06 13:41     ` Oleksandr Natalenko
2020-03-06 16:08       ` Vlastimil Babka
2020-03-09 13:11         ` Oleksandr Natalenko
2020-03-09 15:08           ` Michal Hocko
2020-03-09 15:19             ` Oleksandr Natalenko
2020-03-09 15:42               ` Vlastimil Babka
2020-03-09 16:03                 ` Michal Hocko
2020-06-11  2:21   ` Jann Horn
2020-03-02 21:16 ` [PATCH v7 0/7] introduce memory hinting API for external process Andrew Morton
2020-03-02 21:42   ` Minchan Kim

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