linux-kernel - Re: [PATCH] mm/util.c: Add error logs for commitment overflow

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20201002121137.GY20115@casper.infradead.org>
Date:   Fri, 2 Oct 2020 13:11:37 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Pintu Kumar <pintu@...eaurora.org>
Cc:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        linux-mm@...ck.org, pintu.ping@...il.com
Subject: Re: [PATCH] mm/util.c: Add error logs for commitment overflow

On Fri, Oct 02, 2020 at 05:27:41PM +0530, Pintu Kumar wrote:
> This is the output we can see on a 256MB system and with a simple malloc
> and fork program.
> 
> [root@ ~]# cat /proc/meminfo
> MemTotal:         249520 kB   ==> 243MB
> MemFree:          179100 kB
> 
> PPID	PID	USER	RSS	VSZ	STAT	ARGS
>  150	164	root	1440	250580	S	./consume-and-fork.out 243
> 
> __vm_enough_memory: commitment overflow: ppid:150, pid:164, pages:62451
> fork failed[count:0]: Cannot allocate memory

I don't think the __func__ is particularly useful information.  I would
also expect the name of the process to be more interesting than the PID.
And why is the ppid useful?

Wouldn't this message be more useful?

fork: Would overcommit system (pid:162 name:./consume-and-fork.out)

ie put it in dup_mmap() and use current->comm

> +	pr_err_once("%s: commitment overflow: ppid:%d, pid:%d, pages:%ld\n",
> +			__func__, current->parent->pid, current->pid, pages);
> +