The patch titled
Subject: Revert "mm, memory_hotplug: initialize struct pages for the full memory section"
has been added to the -mm tree. Its filename is
revert-mm-memory_hotplug-initialize-struct-pages-for-the-full-memory-section.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/revert-mm-memory_hotplug-initialize-struct-pages-for-the-full-memory-section.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/revert-mm-memory_hotplug-initialize-struct-pages-for-the-full-memory-section.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: Revert "mm, memory_hotplug: initialize struct pages for the full memory section"
This reverts 2830bf6f05fb3e05b ("mm, memory_hotplug: initialize struct
pages for the full memory section").
The underlying assumption that one sparse section belongs into a single
numa node doesn't hold really. Robert Shteynfeld has reported a boot
failure. The boot log was not captured but his memory layout is as
follows:
[ 0.286954] Early memory node ranges
[ 0.286955] node 1: [mem 0x0000000000001000-0x0000000000090fff]
[ 0.286955] node 1: [mem 0x0000000000100000-0x00000000dbdf8fff]
[ 0.286956] node 1: [mem 0x0000000100000000-0x0000001423ffffff]
[ 0.286956] node 0: [mem 0x0000001424000000-0x0000002023ffffff]
This means that node0 starts in the middle of a memory section which is
also in node1. memmap_init_zone tries to initialize padding of a section
even when it is outside of the given pfn range because there are code
paths (e.g. memory hotplug) which assume that the full worth of memory
section is always initialized. In this particular case, though, such a
range is already intialized and most likely already managed by the page
allocator. Scribbling over those pages corrupts the internal state and
likely blows up when any of those pages gets used.
Link: http://lkml.kernel.org/r/20190125181549.GE20411@xxxxxxxxxxxxxx
Fixes: 2830bf6f05fb ("mm, memory_hotplug: initialize struct pages for the full memory section")
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: Robert Shteynfeld <robert.shteynfeld@xxxxxxxxx>
Cc: Mikhail Zaslonko <zaslonko@xxxxxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Cc: Mikhail Gavrilov <mikhail.v.gavrilov@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Cc: Pasha Tatashin <Pavel.Tatashin@xxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 12 ------------
1 file changed, 12 deletions(-)
--- a/mm/page_alloc.c~revert-mm-memory_hotplug-initialize-struct-pages-for-the-full-memory-section
+++ a/mm/page_alloc.c
@@ -5701,18 +5701,6 @@ void __meminit memmap_init_zone(unsigned
cond_resched();
}
}
-#ifdef CONFIG_SPARSEMEM
- /*
- * If the zone does not span the rest of the section then
- * we should at least initialize those pages. Otherwise we
- * could blow up on a poisoned page in some paths which depend
- * on full sections being initialized (e.g. memory hotplug).
- */
- while (end_pfn % PAGES_PER_SECTION) {
- __init_single_page(pfn_to_page(end_pfn), end_pfn, zone, nid);
- end_pfn++;
- }
-#endif
}
#ifdef CONFIG_ZONE_DEVICE
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-memory_hotplug-is_mem_section_removable-do-not-pass-the-end-of-a-zone.patch
revert-mm-memory_hotplug-initialize-struct-pages-for-the-full-memory-section.patch
mm-oom-marks-all-killed-tasks-as-oom-victims.patch
memcg-do-not-report-racy-no-eligible-oom-tasks.patch
