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From: Florian Weimer <fw@deneb.enyo.de>
To: Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [PATCH v2] linux: Fix __closefrom_fallback iterates until max
 int (BZ#28993)
References: <20220324110907.169470-1-adhemerval.zanella@linaro.org>
Date: Thu, 24 Mar 2022 12:25:01 +0100
In-Reply-To: <20220324110907.169470-1-adhemerval.zanella@linaro.org>
 (Adhemerval Zanella via Libc-alpha's message of "Thu, 24 Mar 2022
 08:09:07 -0300")
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* Adhemerval Zanella via Libc-alpha:

> The __closefrom_fallback tries to get a available file descriptor
> if the initial open ("/proc/self/fd/", ...) fails.  It assumes the
> failure would be only if procfs is not mount (ENOENT), however if
> the the proc file is not accessible (due some other kernel filtering
> such apparmor) it will iterate over a potentially large file set
> issuing close calls.
>
> It should only try the close fallback if open returns EMFILE.

I disagree.  If there are performance issues due to the current code,
people should fix their container hosts.