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| author | Pingfan Liu <kernelfans@gmail.com> | 2020-01-30 22:11:10 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-01-31 10:30:36 -0800 |
| commit | 1f503443e7df8dc8366608b4d810ce2d6669827c (patch) | |
| tree | ac9f640d1d412b683aeed1ea209cd5f867a54a77 /mm/sparse.c | |
| parent | c7a91bc7c2e17e0a9c8b9745a2cb118891218fd1 (diff) | |
| download | lwn-1f503443e7df8dc8366608b4d810ce2d6669827c.tar.gz lwn-1f503443e7df8dc8366608b4d810ce2d6669827c.zip | |
mm/sparse.c: reset section's mem_map when fully deactivated
After commit ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug"),
when a mem section is fully deactivated, section_mem_map still records
the section's start pfn, which is not used any more and will be
reassigned during re-addition.
In analogy with alloc/free pattern, it is better to clear all fields of
section_mem_map.
Beside this, it breaks the user space tool "makedumpfile" [1], which
makes assumption that a hot-removed section has mem_map as NULL, instead
of checking directly against SECTION_MARKED_PRESENT bit. (makedumpfile
will be better to change the assumption, and need a patch)
The bug can be reproduced on IBM POWERVM by "drmgr -c mem -r -q 5" ,
trigger a crash, and save vmcore by makedumpfile
[1]: makedumpfile, commit e73016540293 ("[v1.6.7] Update version")
Link: http://lkml.kernel.org/r/1579487594-28889-1-git-send-email-kernelfans@gmail.com
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/sparse.c')
| -rw-r--r-- | mm/sparse.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/sparse.c b/mm/sparse.c index 3822ecbd8a1f..3918fc3eaef1 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -789,7 +789,7 @@ 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); - ms->section_mem_map = sparse_encode_mem_map(NULL, section_nr); + ms->section_mem_map = (unsigned long)NULL; } if (section_is_early && memmap) |