From: Baoquan He <bhe@redhat.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, mpe@ellerman.id.au,
linuxppc-dev@lists.ozlabs.org,
Sachin Sant <sachinp@linux.vnet.ibm.com>,
dan.j.williams@intel.com
Subject: Re: [PATCH] mm/sparse: Fix kernel crash with pfn_section_valid check
Date: Wed, 25 Mar 2020 15:37:07 +0800 [thread overview]
Message-ID: <20200325073707.GI3039@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20200325070643.GH3039@MiWiFi-R3L-srv>
On 03/25/20 at 03:06pm, Baoquan He wrote:
> On 03/25/20 at 08:49am, Aneesh Kumar K.V wrote:
> > mm/sparse.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/mm/sparse.c b/mm/sparse.c
> > index aadb7298dcef..3012d1f3771a 100644
> > --- a/mm/sparse.c
> > +++ b/mm/sparse.c
> > @@ -781,6 +781,8 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> > ms->usage = NULL;
> > }
> > memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
> > + /* Mark the section invalid */
> > + ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
>
> Not sure if we should add checking in valid_section() or pfn_valid(),
> e.g check ms->usage validation too. Otherwise, this fix looks good to
> me.
With SPASEMEM_VMEMAP enabled, we should do validation check on ms->usage
before checking any subsection is valid. Since now we do have case
in which ms->usage is released, people still try to check it.
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f0a2c184eb9a..d79bd938852e 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1306,6 +1306,8 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
{
int idx = subsection_map_index(pfn);
+ if (!ms->usage)
+ return 0;
return test_bit(idx, ms->usage->subsection_map);
}
#else
next prev parent reply other threads:[~2020-03-25 7:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 3:19 [PATCH] mm/sparse: Fix kernel crash with pfn_section_valid check Aneesh Kumar K.V
2020-03-25 7:06 ` Baoquan He
2020-03-25 7:37 ` Baoquan He [this message]
2020-03-25 8:12 ` Aneesh Kumar K.V
2020-03-25 8:36 ` Baoquan He
2020-03-26 0:38 ` Andrew Morton
2020-03-26 9:40 ` Michal Hocko
2020-03-26 9:56 ` Aneesh Kumar K.V
2020-03-26 10:16 ` Michal Hocko
2020-03-26 10:50 ` Michal Hocko
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