From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 21/25] mm/madvise: support both pid and pidfd for process_madvise Date: Wed, 10 Jun 2020 18:42:29 -0700 Message-ID: <20200611014229.aHtg-8rXi%akpm@linux-foundation.org> References: <20200610184053.3fa7368ab80e23bfd44de71f@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:51340 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726268AbgFKBmc (ORCPT ); Wed, 10 Jun 2020 21:42:32 -0400 In-Reply-To: <20200610184053.3fa7368ab80e23bfd44de71f@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, alexander.h.duyck@linux.intel.com, axboe@kernel.dk, bgeffon@google.com, christian.brauner@ubuntu.com, christian@brauner.io, dancol@google.com, hannes@cmpxchg.org, jannh@google.com, joaodias@google.com, joel@joelfernandes.org, ktkhai@virtuozzo.com, linux-man@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, minchan@kernel.org, mm-commits@vger.kernel.org, oleksandr@redhat.com, shakeelb@google.com, sj38.park@gmail.com, sjpark@amazon.de, sonnyrao@google.com, sspatil@google.com, surenb@google.com, timmurray@google.com, torvalds@linux-foundation.org, vbabka@suse.cz From: Minchan Kim Subject: mm/madvise: support both pid and pidfd for process_madvise 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(idtype_t idtype, id_t id, void *addr, size_t length, int advice, unsigned long flags); @which is actually idtype_t for userspace library and currently, it supports P_PID and P_PIDFD. [1] https://lore.kernel.org/linux-mm/9d849087-3359-c4ab-fbec-859e8186c509@virtuozzo.com/ Link: http://lkml.kernel.org/r/20200302193630.68771-6-minchan@kernel.org Signed-off-by: Minchan Kim Suggested-by: Kirill Tkhai Reviewed-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka Cc: Christian Brauner Cc: Alexander Duyck Cc: Brian Geffon Cc: Daniel Colascione Cc: Jann Horn Cc: Jens Axboe Cc: Joel Fernandes Cc: Johannes Weiner Cc: John Dias Cc: Michal Hocko Cc: Oleksandr Natalenko Cc: Sandeep Patil Cc: SeongJae Park Cc: SeongJae Park Cc: Shakeel Butt Cc: Sonny Rao Cc: Tim Murray Cc: Christian Brauner Cc: Signed-off-by: Andrew Morton --- include/linux/syscalls.h | 3 ++- mm/madvise.c | 36 +++++++++++++++++++++++------------- 2 files changed, 25 insertions(+), 14 deletions(-) --- a/include/linux/syscalls.h~mm-support-both-pid-and-pidfd-for-process_madvise +++ a/include/linux/syscalls.h @@ -878,7 +878,8 @@ 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, --- a/mm/madvise.c~mm-support-both-pid-and-pidfd-for-process_madvise +++ a/mm/madvise.c @@ -1208,11 +1208,10 @@ SYSCALL_DEFINE3(madvise, unsigned long, 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; @@ -1223,20 +1222,31 @@ SYSCALL_DEFINE5(process_madvise, int, pi if (!process_madvise_behavior_valid(behavior)) return -EINVAL; - f = fdget(pidfd); - if (!f.file) - return -EBADF; - - pid = pidfd_pid(f.file); - if (IS_ERR(pid)) { - ret = PTR_ERR(pid); - goto fdput; + 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_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); @@ -1249,7 +1259,7 @@ SYSCALL_DEFINE5(process_madvise, int, pi mmput(mm); release_task: put_task_struct(task); -fdput: - fdput(f); +put_pid: + put_pid(pid); return ret; } _