On Thu, Dec 03, 2020 at 03:00:25AM -0800, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: bfd521e1 Add linux-next specific files for 20201203 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=14d5d403500000 > kernel config: https://syzkaller.appspot.com/x/.config?x=76090eb4ba939f87 > dashboard link: https://syzkaller.appspot.com/bug?extid=86800a8349c0f3f9466e > compiler: gcc (GCC) 10.1.0-syz 20200507 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+86800a8349c0f3f9466e@xxxxxxxxxxxxxxxxxxxxxxxxx ... > page:ffffea0000000000 is uninitialized and poisoned > raw: ffffffffffffffff ffffea0000000008 ffffea0000000008 ffffffffffffffff > raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff > page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page)) > ------------[ cut here ]------------ > kernel BUG at include/linux/page-flags.h:356! Yeah, the change to initialization of "unavailable" memory missed pfn 0 :( This should fix it: >From 84a1c2531374706f3592a638523278aa29aaa448 Mon Sep 17 00:00:00 2001 From: Mike Rapoport <rppt@xxxxxxxxxxxxx> Date: Thu, 3 Dec 2020 11:40:17 +0200 Subject: [PATCH] fixup for "mm: refactor initialization of stuct page for holes" Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> --- mm/page_alloc.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ce2bdaabdf96..86fde4424e87 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6227,7 +6227,8 @@ void __init __weak memmap_init(unsigned long size, int nid, unsigned long zone, unsigned long range_start_pfn) { - unsigned long start_pfn, end_pfn, next_pfn = 0; + static unsigned long hole_start_pfn; + unsigned long start_pfn, end_pfn; unsigned long range_end_pfn = range_start_pfn + size; u64 pgcnt = 0; int i; @@ -6235,7 +6236,6 @@ void __init __weak memmap_init(unsigned long size, int nid, for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) { start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn); end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn); - next_pfn = clamp(next_pfn, range_start_pfn, range_end_pfn); if (end_pfn > start_pfn) { size = end_pfn - start_pfn; @@ -6243,10 +6243,10 @@ void __init __weak memmap_init(unsigned long size, int nid, MEMINIT_EARLY, NULL, MIGRATE_MOVABLE); } - if (next_pfn < start_pfn) - pgcnt += init_unavailable_range(next_pfn, start_pfn, - zone, nid); - next_pfn = end_pfn; + if (hole_start_pfn < start_pfn) + pgcnt += init_unavailable_range(hole_start_pfn, + start_pfn, zone, nid); + hole_start_pfn = end_pfn; } /* @@ -6256,8 +6256,8 @@ void __init __weak memmap_init(unsigned long size, int nid, * considered initialized. Make sure that memmap has a well defined * state. */ - if (next_pfn < range_end_pfn) - pgcnt += init_unavailable_range(next_pfn, range_end_pfn, + if (hole_start_pfn < range_end_pfn) + pgcnt += init_unavailable_range(hole_start_pfn, range_end_pfn, zone, nid); if (pgcnt) -- 2.28.0
