From: Michal Hocko <mhocko@kernel.org>
To: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Cc: Coly Li <colyli@suse.de>,
songliubraving@fb.com, linux-raid@vger.kernel.org,
Kent Overstreet <kent.overstreet@gmail.com>
Subject: Re: [PATCH] raid5: use memalloc_noio_save()/restore in resize_chunks()
Date: Wed, 15 Apr 2020 13:48:14 +0200 [thread overview]
Message-ID: <20200415114814.GJ4629@dhcp22.suse.cz> (raw)
In-Reply-To: <204e9fd0-3712-4864-2bf5-38913511e658@cloud.ionos.com>
On Thu 09-04-20 23:38:13, Guoqing Jiang wrote:
[...]
> Not know memalloc_noio_{save,restore} well, but I guess it is better
> to use them to mark a small scope, just my two cents.
This would go against the intentio of the api. It is really meant to
define reclaim recursion problematic scope. If there is a clear entry
point where any further allocation recursing to FS/IO could deadlock
then it should be used at that level. This might be a lock which is
taken from the reclaim or like this case a device is suspended and no IO
is processed so anything that would wait for an IO or rely on IO making
progress in the reclaim path would deadlock.
Please have a look at Documentation/core-api/gfp_mask-from-fs-io.rst
and let me know is something could be made more clear or explicit.
I am more than happy to improve the documentation.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-04-15 11:48 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-02 8:13 [PATCH] raid5: use memalloc_noio_save()/restore in resize_chunks() Coly Li
2020-04-03 13:17 ` kbuild test robot
2020-04-05 15:53 ` Guoqing Jiang
2020-04-07 15:09 ` Coly Li
2020-04-09 21:38 ` Guoqing Jiang
2020-04-10 9:36 ` Coly Li
2020-04-15 11:48 ` Michal Hocko [this message]
2020-04-15 14:10 ` Guoqing Jiang
2020-04-15 14:23 ` Michal Hocko
2020-04-15 14:57 ` Guoqing Jiang
2020-04-30 6:36 ` Song Liu
2020-04-05 17:43 ` Song Liu
2020-04-07 14:42 ` Coly Li
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