From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id 2F7666B0005 for ; Tue, 21 Jun 2016 05:28:14 -0400 (EDT) Received: by mail-io0-f199.google.com with SMTP id k78so12730568ioi.2 for ; Tue, 21 Jun 2016 02:28:14 -0700 (PDT) Received: from out4439.biz.mail.alibaba.com (out4439.biz.mail.alibaba.com. [47.88.44.39]) by mx.google.com with ESMTP id h80si38969383ioh.38.2016.06.21.02.28.11 for ; Tue, 21 Jun 2016 02:28:13 -0700 (PDT) Reply-To: "Hillf Danton" From: "Hillf Danton" References: <06be01d1cb9c$8f235850$ad6a08f0$@alibaba-inc.com> In-Reply-To: <06be01d1cb9c$8f235850$ad6a08f0$@alibaba-inc.com> Subject: Re: [PATCH 03/10] proc, oom_adj: extract oom_score_adj setting into a helper Date: Tue, 21 Jun 2016 17:27:57 +0800 Message-ID: <06bf01d1cb9f$32a49320$97edb960$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Language: zh-cn Sender: owner-linux-mm@kvack.org List-ID: To: 'Michal Hocko' Cc: 'Oleg Nesterov' , linux-kernel , linux-mm@kvack.org > > From: Michal Hocko > > Currently we have two proc interfaces to set oom_score_adj. The legacy > /proc//oom_adj and /proc//oom_score_adj which both have their > specific handlers. Big part of the logic is duplicated so extract the > common code into __set_oom_adj helper. Legacy knob still expects some > details slightly different so make sure those are handled same way - e.g. > the legacy mode ignores oom_score_adj_min and it warns about the usage. > > This patch shouldn't introduce any functional changes. > > Acked-by: Oleg Nesterov > Signed-off-by: Michal Hocko > --- > fs/proc/base.c | 94 +++++++++++++++++++++++++++------------------------------- > 1 file changed, 43 insertions(+), 51 deletions(-) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index 968d5ea06e62..a6a8fbdd5a1b 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -1037,7 +1037,47 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count, > return simple_read_from_buffer(buf, count, ppos, buffer, len); > } > > -static DEFINE_MUTEX(oom_adj_mutex); > +static int __set_oom_adj(struct file *file, int oom_adj, bool legacy) > +{ > + static DEFINE_MUTEX(oom_adj_mutex); Writers are not excluded for readers! Is this a hot path? > + struct task_struct *task; > + int err = 0; > + > + task = get_proc_task(file_inode(file)); > + if (!task) > + return -ESRCH; > + > + mutex_lock(&oom_adj_mutex); > + if (legacy) { > + if (oom_adj < task->signal->oom_score_adj && > + !capable(CAP_SYS_RESOURCE)) { > + err = -EACCES; > + goto err_unlock; > + } > + /* > + * /proc/pid/oom_adj is provided for legacy purposes, ask users to use > + * /proc/pid/oom_score_adj instead. > + */ > + pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n", > + current->comm, task_pid_nr(current), task_pid_nr(task), > + task_pid_nr(task)); > + } else { > + if ((short)oom_adj < task->signal->oom_score_adj_min && > + !capable(CAP_SYS_RESOURCE)) { > + err = -EACCES; > + goto err_unlock; > + } > + } > + > + task->signal->oom_score_adj = oom_adj; > + if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE)) > + task->signal->oom_score_adj_min = (short)oom_adj; > + trace_oom_score_adj_update(task); > +err_unlock: > + mutex_unlock(&oom_adj_mutex); > + put_task_struct(task); > + return err; > +} > > /* > * /proc/pid/oom_adj exists solely for backwards compatibility with previous > @@ -1052,7 +1092,6 @@ static DEFINE_MUTEX(oom_adj_mutex); > static ssize_t oom_adj_write(struct file *file, const char __user *buf, > size_t count, loff_t *ppos) > { > - struct task_struct *task; > char buffer[PROC_NUMBUF]; > int oom_adj; > int err; > @@ -1074,12 +1113,6 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf, > goto out; > } > > - task = get_proc_task(file_inode(file)); > - if (!task) { > - err = -ESRCH; > - goto out; > - } > - > /* > * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum > * value is always attainable. > @@ -1089,26 +1122,7 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf, > else > oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE; > > - mutex_lock(&oom_adj_mutex); > - if (oom_adj < task->signal->oom_score_adj && > - !capable(CAP_SYS_RESOURCE)) { > - err = -EACCES; > - goto err_unlock; > - } > - > - /* > - * /proc/pid/oom_adj is provided for legacy purposes, ask users to use > - * /proc/pid/oom_score_adj instead. > - */ > - pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n", > - current->comm, task_pid_nr(current), task_pid_nr(task), > - task_pid_nr(task)); > - > - task->signal->oom_score_adj = oom_adj; > - trace_oom_score_adj_update(task); > -err_unlock: > - mutex_unlock(&oom_adj_mutex); > - put_task_struct(task); > + err = __set_oom_adj(file, oom_adj, true); > out: > return err < 0 ? err : count; > } > @@ -1138,7 +1152,6 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf, > static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, > size_t count, loff_t *ppos) > { > - struct task_struct *task; > char buffer[PROC_NUMBUF]; > int oom_score_adj; > int err; > @@ -1160,28 +1173,7 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, > goto out; > } > > - task = get_proc_task(file_inode(file)); > - if (!task) { > - err = -ESRCH; > - goto out; > - } > - > - mutex_lock(&oom_adj_mutex); > - if ((short)oom_score_adj < task->signal->oom_score_adj_min && > - !capable(CAP_SYS_RESOURCE)) { > - err = -EACCES; > - goto err_unlock; > - } > - > - task->signal->oom_score_adj = (short)oom_score_adj; > - if (has_capability_noaudit(current, CAP_SYS_RESOURCE)) > - task->signal->oom_score_adj_min = (short)oom_score_adj; > - > - trace_oom_score_adj_update(task); > - > -err_unlock: > - mutex_unlock(&oom_adj_mutex); > - put_task_struct(task); > + err = __set_oom_adj(file, oom_score_adj, false); > out: > return err < 0 ? err : count; > } > -- > 2.8.1 > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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