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  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]
Date:   Wed, 20 May 2020 08:40:39 +0000
From:   Alex Zhuravlev <>
To:     Andreas Dilger <>
CC:     Alex Zhuravlev <>,
        Ritesh Harjani <>,
        "" <>
Subject: Re: [PATCH 2/2] ext4: skip non-loaded groups at cr=0/1

> On 17 May 2020, at 10:55, Andreas Dilger <> wrote:
> The question is whether this is situation is affecting only a few inode
> allocations for a short time after mount, or does this persist for a long
> time?  I think that it _should_ be only a short time, because these other
> threads should all start prefetch on their preferred groups, so even if a
> few inodes have their blocks allocated in the "wrong" group, it shouldn't
> be a long term problem since the prefetched bitmaps will finish loading
> and allow the blocks to be allocated, or skipped if group is fragmented.

Yes, that’s the idea - there is a short window when buddy data is being
populated. And for each “cluster” (not just a single group) prefetching
will be initiated by allocation.
It’s possible that some number of inodes will get “bad” blocks right after
after mount.
If you think this is a bad scenario I can introduce couple more things:
1) few times discussed prefetching thread
2) let mballoc wait for the goal group to get ready - this essentials one
    more check in ext4_mb_good_group()

Thanks, Alex

Powered by blists - more mailing lists