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

[Ming Lei]

On Fri, Apr 02, 2021 at 07:27:30PM +0200, Christoph Hellwig wrote:
> 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@xxxxxxxxxx>
> > > 
> > > 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.

We still may shutdown blktrace if current is the last opener, otherwise
new blktrace can't be started and memory should be leaked forever, and
what do you think of the revised version?