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Message-ID: <YFuZua1TIEkXtqoL@google.com>
Date: Wed, 24 Mar 2021 12:57:45 -0700
From: Minchan Kim <minchan@...nel.org>
To: Dmitry Osipenko <digetx@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-mm <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>, gregkh@...uxfoundation.org,
surenb@...gle.com, joaodias@...gle.com, jhubbard@...dia.com,
willy@...radead.org
Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count
On Wed, Mar 24, 2021 at 10:49:58PM +0300, Dmitry Osipenko wrote:
> 24.03.2021 22:43, Dmitry Osipenko пишет:
> > 24.03.2021 22:20, Minchan Kim пишет:
> >> static int __init cma_sysfs_init(void)
> >> {
> >> - int i = 0;
> >> + struct kobject *cma_kobj_root;
> >> + struct cma_kobject *cma_kobj;
> >> struct cma *cma;
> >> + unsigned int i;
> >
> >> while (--i >= 0) {
> >
> > Do you realize that this doesn't work anymore?
> >
> >> cma = &cma_areas[i];
> >> - kobject_put(&cma->stat->kobj);
> >> - }
> >>
> >> - kfree(cma_stats);
> >> - kobject_put(cma_kobj);
> >> + kobject_put(&cma->cma_kobj->kobj);
> >> + kfree(cma->cma_kobj);
> >
> > Freeing a null pointer?
> >
> >> + cma->cma_kobj = NULL;
> >> + }
> >> + kobject_put(cma_kobj_root);
> >
>
> Please try to simulate the errors and check that error path is working
> properly in the next version.
>
> Alternatively, we could remove the cma_kobj_release entirely, like Greg
> suggested previously, and then don't care about cleaning up at all.
Does he suggested it to remove cma_kobj_release?(Initially, I did but
was rejected from Greg)
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