linux-kernel - [PATCH] proc: add a schedule point in proc_pid

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Message-ID: <1484238380.15816.42.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Thu, 12 Jan 2017 08:26:20 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH] proc: add a schedule point in proc_pid_readdir()

From: Eric Dumazet <edumazet@...gle.com>

We have seen proc_pid_readdir() invocations holding cpu for more
than 50 ms. Add a cond_resched() to be gentle with other tasks.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 fs/proc/base.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8e7e61b28f31..f204f80d397b 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3179,6 +3179,7 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
 		char name[PROC_NUMBUF];
 		int len;
+		cond_resched();
 		if (!has_pid_permissions(ns, iter.task, 2))
 			continue;