linux-kernel - Re: [PATCH 1/2] block: shutdown blktrace in case of fatal signal pending

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Message-ID: <20210402172730.GA22923@lst.de>
Date:   Fri, 2 Apr 2021 19:27:30 +0200
From:   Christoph Hellwig <hch@....de>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] block: shutdown blktrace in case of fatal signal
 pending

On Wed, Mar 31, 2021 at 08:16:50AM +0800, Ming Lei wrote:
> On Tue, Mar 30, 2021 at 06:53:30PM +0200, Christoph Hellwig wrote:
> > On Tue, Mar 23, 2021 at 04:14:39PM +0800, Ming Lei wrote:
> > > blktrace may allocate lots of memory, if the process is terminated
> > > by user or OOM, we need to provide one chance to remove the trace
> > > buffer, otherwise memory leak may be caused.
> > > 
> > > Fix the issue by shutdown blktrace in case of task exiting in
> > > blkdev_close().
> > > 
> > > Signed-off-by: Ming Lei <ming.lei@...hat.com>
> > 
> > This just seems weird.  blktrace has no relationship to open
> > block device instances.
> 
> blktrace still needs to open one blkdev, then send its own ioctl
> commands to block layer. In case of OOM, the allocated memory in
> these ioctl commands won't be released.
> 
> Or any other suggestion?

Not much we can do there I think.  If we want to autorelease memory
it needs to be an API that ties the memory allocation to an FD.