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  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:   Mon, 12 Oct 2020 15:40:27 +0800
From:   Coly Li <colyli@...e.de>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Kent Overstreet <kent.overstreet@...il.com>, x86@...nel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        kvm@...r.kernel.org, netdev@...r.kernel.org, bpf@...r.kernel.org,
        kexec@...ts.infradead.org, linux-bcache@...r.kernel.org,
        linux-mtd@...ts.infradead.org, devel@...verdev.osuosl.org,
        linux-efi@...r.kernel.org, linux-mmc@...r.kernel.org,
        linux-scsi@...r.kernel.org, target-devel@...r.kernel.org,
        linux-nfs@...r.kernel.org, ceph-devel@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-aio@...ck.org,
        io-uring@...r.kernel.org, linux-erofs@...ts.ozlabs.org,
        linux-um@...ts.infradead.org, linux-ntfs-dev@...ts.sourceforge.net,
        reiserfs-devel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-nilfs@...r.kernel.org, cluster-devel@...hat.com,
        ecryptfs@...r.kernel.org, linux-cifs@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-afs@...ts.infradead.org,
        linux-rdma@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        xen-devel@...ts.xenproject.org, linux-cachefs@...hat.com,
        samba-technical@...ts.samba.org, intel-wired-lan@...ts.osuosl.org
Subject: Re: [PATCH RFC PKS/PMEM 48/58] drivers/md: Utilize new kmap_thread()

On 2020/10/12 13:28, Ira Weiny wrote:
> On Sat, Oct 10, 2020 at 10:20:34AM +0800, Coly Li wrote:
>> On 2020/10/10 03:50, ira.weiny@...el.com wrote:
>>> From: Ira Weiny <ira.weiny@...el.com>
>>>
>>> These kmap() calls are localized to a single thread.  To avoid the over
>>> head of global PKRS updates use the new kmap_thread() call.
>>>
>>
>> Hi Ira,
>>
>> There were a number of options considered.
>>
>> 1) Attempt to change all the thread local kmap() calls to kmap_atomic()
>> 2) Introduce a flags parameter to kmap() to indicate if the mapping
>> should be global or not
>> 3) Change ~20-30 call sites to 'kmap_global()' to indicate that they
>> require a global mapping of the pages
>> 4) Change ~209 call sites to 'kmap_thread()' to indicate that the
>> mapping is to be used within that thread of execution only
>>
>>
>> I copied the above information from patch 00/58 to this message. The
>> idea behind kmap_thread() is fine to me, but as you said the new api is
>> very easy to be missed in new code (even for me). I would like to be
>> supportive to option 2) introduce a flag to kmap(), then we won't forget
>> the new thread-localized kmap method, and people won't ask why a
>> _thread() function is called but no kthread created.
> 
> Thanks for the feedback.
> 
> I'm going to hold off making any changes until others weigh in.  FWIW, I kind
> of like option 2 as well.  But there is already kmap_atomic() so it seemed like
> kmap_XXXX() was more in line with the current API.

I understand it now, the idea is fine to me.

Acked-by: Coly Li <colyli@...e.de>

Thanks.

Coly Li

Powered by blists - more mailing lists