linux-kernel - Re: Regression from 2.6.36

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Date:	Thu, 07 Apr 2011 14:13:46 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Américo Wang <xiyou.wangcong@...il.com>
Cc:	Jiri Slaby <jslaby@...e.cz>, azurIt <azurit@...ox.sk>,
	linux-kernel@...r.kernel.org, Changli Gao <xiaosuo@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org, Jiri Slaby <jirislaby@...il.com>
Subject: Re: Regression from 2.6.36

Le jeudi 07 avril 2011 à 13:57 +0200, Eric Dumazet a écrit :

> We had a similar memory problem in fib_trie in the past  : We force a
> synchronize_rcu() every XXX Mbytes allocated to make sure we dont have
> too much ram waiting to be freed in rcu queues.

This was done in commit c3059477fce2d956
(ipv4: Use synchronize_rcu() during trie_rebalance())

It was possible in fib_trie because we hold RTNL lock, so managing
a counter was free.

In fs case, we might use a percpu_counter if we really want to limit the
amount of space.

Now, I am not even sure we should care that much and could just forget
about this high order pages use.


diff --git a/fs/file.c b/fs/file.c
index 0be3447..7ba26fe 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -41,12 +41,6 @@ static DEFINE_PER_CPU(struct fdtable_defer,
fdtable_defer_list);
 
 static inline void *alloc_fdmem(unsigned int size)
 {
-	void *data;
-
-	data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN);
-	if (data != NULL)
-	return data;
-
 	return vmalloc(size);
 }


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