linux-kernel - Re: [PATCH] mm/khugepaged: add tracepoint to collapse

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] [day] [month] [year] [list]

Message-ID: <Y1bNlKl1XSCxhaVT@biggie>
Date:   Mon, 24 Oct 2022 23:08:28 +0530
From:   Gautam Menghani <gautammenghani201@...il.com>
To:     Zach O'Keefe <zokeefe@...gle.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>, akpm@...ux-foundation.org,
        mhiramat@...nel.org, shy828301@...il.com, vbabka@...e.cz,
        david@...hat.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/khugepaged: add tracepoint to collapse_file()

On Mon, Oct 24, 2022 at 09:44:16AM -0700, Zach O'Keefe wrote:
> Thanks for your mail, Gautam.
> 
> > I try to keep dereferences out of the calling path as much as possible
> > (adds to I$ at the call site).
> 
> This was probably due to the way I handled
> trace_mm_khugepaged_scan_file(). Perhaps that can be cleaned up at the
> same time as this patch, for consistency.
>
Yes sure I'll send a patch for cleaning this up.
 
> Also, no qualms about adding this tracepoint; there are a few scan
> result codes that overlap between hpage_collapse_scan_file() and those
> possibly returned in collapse_file() such that, if we only have the
> one tracepoint in hpage_collapse_scan_file(), it could be ambiguous
> what callsite the error path stemmed from. Luckily this hasn't been an
> issue thus far.
> 
> Lastly, a few other items we might care about capturing:
> 
> - is_shmem (perhaps the filename is enough to know this - but I know
> at least once during development I was caught off-guard b/c a mount I
> thought to be file-backed turned out to be tmpfs (and something I
> didn't think to question until I had wasted some time on other
> paths)).
> - index

Yes noted.