From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guoqing Jiang Subject: Re: [PATCH] raid5: use memalloc_noio_save()/restore in resize_chunks() Date: Wed, 15 Apr 2020 16:57:15 +0200 Message-ID: References: <20200402081312.32709-1-colyli@suse.de> <5f27365b-768f-eb69-36ec-f4ed0c292c60@suse.de> <204e9fd0-3712-4864-2bf5-38913511e658@cloud.ionos.com> <20200415114814.GJ4629@dhcp22.suse.cz> <20200415142303.GN4629@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200415142303.GN4629@dhcp22.suse.cz> Content-Language: en-US Sender: linux-raid-owner@vger.kernel.org To: Michal Hocko Cc: Coly Li , songliubraving@fb.com, linux-raid@vger.kernel.org, Kent Overstreet List-Id: linux-raid.ids On 15.04.20 16:23, Michal Hocko wrote: > On Wed 15-04-20 16:10:08, Guoqing Jiang wrote: >> On 15.04.20 13:48, Michal Hocko wrote: >>> 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. >> Well, in current proposal, the scope is just when >> scribble_allo/kvmalloc_array is called. >> >> memalloc_noio_save >> scribble_allo/kvmalloc_array >> memalloc_noio_restore >> >> With the new proposal, the marked scope would be bigger than current one >> since there >> are lots of places call mddev_suspend/resume. >> >> mddev_suspend >> memalloc_noio_save >> ... >> memalloc_noio_restore >> mddev_resume >> >> IMHO, if the current proposal works then what is the advantage to increase >> the scope. > The advantage is twofold. It serves the documentation purpose because it > is clear _what_ and _why_ is the actual allocation restricted context. > In this case mddev_{suspend,resume} because XYZ and you do not have to > care about __GFP_IO for _any_ allocation inside the scope. Personally, I'd prefer fine grained protection scope, anyway just my own flavor. And I think Song has his opinion about the proposal, I will respect his decision. Thanks, Guoqing