From: Pasha Tatashin Pavel.Tatashin@microsoft.com Subject: mm: disable deferred struct page for 32-bit arches

Deferred struct page init is needed only on systems with large amount of physical memory to improve boot performance. 32-bit systems do not benefit from this feature.

Jiri reported a problem where deferred struct pages do not work well with x86-32:

[ 0.035162] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes) [ 0.035725] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes) [ 0.036269] Initializing CPU#0 [ 0.036513] Initializing HighMem for node 0 (00036ffe:0007ffe0) [ 0.038459] page:f6780000 is uninitialized and poisoned [ 0.038460] raw: ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff [ 0.039509] page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page)) [ 0.040038] ------------[ cut here ]------------ [ 0.040399] kernel BUG at include/linux/page-flags.h:293! [ 0.040823] invalid opcode: 0000 [#1] SMP PTI [ 0.041166] CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.0-rc1_pt_jiri #9 [ 0.041694] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014 [ 0.042496] EIP: free_highmem_page+0x64/0x80 [ 0.042839] Code: 13 46 d8 c1 e8 18 5d 83 e0 03 8d 04 c0 c1 e0 06 ff 80 ec 5f 44 d8 c3 8d b4 26 00 00 00 00 ba 08 65 28 d8 89 d8 e8 fc 71 02 00 <0f> 0b 8d 76 00 8d bc 27 00 00 00 00 ba d0 b1 26 d8 89 d8 e8 e4 71 [ 0.044338] EAX: 0000003c EBX: f6780000 ECX: 00000000 EDX: d856cbe8 [ 0.044868] ESI: 0007ffe0 EDI: d838df20 EBP: d838df00 ESP: d838defc [ 0.045372] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00210086 [ 0.045913] CR0: 80050033 CR2: 00000000 CR3: 18556000 CR4: 00040690 [ 0.046413] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [ 0.046913] DR6: fffe0ff0 DR7: 00000400 [ 0.047220] Call Trace: [ 0.047419] add_highpages_with_active_regions+0xbd/0x10d [ 0.047854] set_highmem_pages_init+0x5b/0x71 [ 0.048202] mem_init+0x2b/0x1e8 [ 0.048460] start_kernel+0x1d2/0x425 [ 0.048757] i386_start_kernel+0x93/0x97 [ 0.049073] startup_32_smp+0x164/0x168 [ 0.049379] Modules linked in: [ 0.049626] ---[ end trace 337949378db0abbb ]---

We free highmem pages before their struct pages are initialized:

mem_init() set_highmem_pages_init() add_highpages_with_active_regions() free_highmem_page() .. Access uninitialized struct page here..

Because there is no reason to have this feature on 32-bit systems, just disable it.

Link: http://lkml.kernel.org/r/20180831150506.31246-1-pavel.tatashin@microsoft.com Fixes: 2e3ca40f03bb ("mm: relax deferred struct page requirements") Signed-off-by: Pavel Tatashin pavel.tatashin@microsoft.com Reported-by: Jiri Slaby jslaby@suse.cz Acked-by: Michal Hocko mhocko@suse.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

diff -puN mm/Kconfig~mm-disable-deferred-struct-page-for-32-bit-arches mm/Kconfig --- a/mm/Kconfig~mm-disable-deferred-struct-page-for-32-bit-arches +++ a/mm/Kconfig @@ -637,6 +637,7 @@ config DEFERRED_STRUCT_PAGE_INIT depends on NO_BOOTMEM depends on SPARSEMEM depends on !NEED_PER_CPU_KM + depends on 64BIT help Ordinarily all struct pages are initialised during early boot in a single thread. On very large machines this can take a considerable _