linux-kernel - Re: [PATCH 0/6] Overhaul memalloc

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: <20200625203442.GG7703@casper.infradead.org>
Date:   Thu, 25 Jun 2020 21:34:42 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-xfs@...r.kernel.org, dm-devel@...hat.com,
        Mikulas Patocka <mpatocka@...hat.com>,
        Jens Axboe <axboe@...nel.dk>, NeilBrown <neilb@...e.de>,
        Yafang Shao <laoar.shao@...il.com>
Subject: Re: [PATCH 0/6] Overhaul memalloc_no*

On Thu, Jun 25, 2020 at 11:48:32AM -0700, Darrick J. Wong wrote:
> On Thu, Jun 25, 2020 at 12:31:16PM +0100, Matthew Wilcox (Oracle) wrote:
> > I want a memalloc_nowait like we have memalloc_noio and memalloc_nofs
> > for an upcoming patch series, and Jens also wants it for non-blocking
> > io_uring.  It turns out we already have dm-bufio which could benefit
> > from memalloc_nowait, so it may as well go into the tree now.
> > 
> > The biggest problem is that we're basically out of PF_ flags, so we need
> > to find somewhere else to store the PF_MEMALLOC_NOWAIT flag.  It turns
> > out the PF_ flags are really supposed to be used for flags which are
> > accessed from other tasks, and the MEMALLOC flags are only going to
> > be used by this task.  So shuffling everything around frees up some PF
> > flags and generally makes the world a better place.
> 
> So, uh, how does this intersect with the patch "xfs: reintroduce
> PF_FSTRANS for transaction reservation recursion protection" that
> re-adds PF_TRANS because uh I guess we lost some subtlety or another at
> some point?

I don't know.  I read that thread, but I couldn't follow the argument.