On 2020-11-08 07:46, Mike Rapoport wrote:
> On Sat, Nov 07, 2020 at 04:22:06PM +0100, Stefan Agner wrote:
>> Most architectures define MAX_PHYSMEM_BITS in asm/sparsemem.h and don't
>> include it in asm/pgtable.h. Include asm/sparsemem.h directly to get
>> the MAX_PHYSMEM_BITS define on all architectures.
>>
>> This fixes a crash when accessing zram on 32-bit ARM platform with LPAE and
>> more than 4GB of memory:
>> Unable to handle kernel NULL pointer dereference at virtual address 00000000
>> pgd = a27bd01c
>> [00000000] *pgd=236a0003, *pmd=1ffa64003
>> Internal error: Oops: 207 [#1] SMP ARM
>> Modules linked in: mdio_bcm_unimac(+) brcmfmac cfg80211 brcmutil raspberrypi_hwmon hci_uart crc32_arm_ce bcm2711_thermal phy_generic genet
>> CPU: 0 PID: 123 Comm: mkfs.ext4 Not tainted 5.9.6 #1
>> Hardware name: BCM2711
>> PC is at zs_map_object+0x94/0x338
>> LR is at zram_bvec_rw.constprop.0+0x330/0xa64
>> pc : [<c0602b38>] lr : [<c0bda6a0>] psr: 60000013
>> sp : e376bbe0 ip : 00000000 fp : c1e2921c
>> r10: 00000002 r9 : c1dda730 r8 : 00000000
>> r7 : e8ff7a00 r6 : 00000000 r5 : 02f9ffa0 r4 : e3710000
>> r3 : 000fdffe r2 : c1e0ce80 r1 : ebf979a0 r0 : 00000000
>> Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
>> Control: 30c5383d Table: 235c2a80 DAC: fffffffd
>> Process mkfs.ext4 (pid: 123, stack limit = 0x495a22e6)
>> Stack: (0xe376bbe0 to 0xe376c000)
>> ...
>> [<c0602b38>] (zs_map_object) from [<c0bda6a0>] (zram_bvec_rw.constprop.0+0x330/0xa64)
>> [<c0bda6a0>] (zram_bvec_rw.constprop.0) from [<c0bdaf78>] (zram_submit_bio+0x1a4/0x40c)
>> [<c0bdaf78>] (zram_submit_bio) from [<c085806c>] (submit_bio_noacct+0xd0/0x3c8)
>> [<c085806c>] (submit_bio_noacct) from [<c08583b0>] (submit_bio+0x4c/0x190)
>> [<c08583b0>] (submit_bio) from [<c06496b4>] (submit_bh_wbc+0x188/0x1b8)
>> [<c06496b4>] (submit_bh_wbc) from [<c064ce98>] (__block_write_full_page+0x340/0x5e4)
>> [<c064ce98>] (__block_write_full_page) from [<c064d3ec>] (block_write_full_page+0x128/0x170)
>> [<c064d3ec>] (block_write_full_page) from [<c0591ae8>] (__writepage+0x14/0x68)
>> [<c0591ae8>] (__writepage) from [<c0593efc>] (write_cache_pages+0x1bc/0x494)
>> [<c0593efc>] (write_cache_pages) from [<c059422c>] (generic_writepages+0x58/0x8c)
>> [<c059422c>] (generic_writepages) from [<c0594c24>] (do_writepages+0x48/0xec)
>> [<c0594c24>] (do_writepages) from [<c0589330>] (__filemap_fdatawrite_range+0xf0/0x128)
>> [<c0589330>] (__filemap_fdatawrite_range) from [<c05894bc>] (file_write_and_wait_range+0x48/0x98)
>> [<c05894bc>] (file_write_and_wait_range) from [<c064f3f8>] (blkdev_fsync+0x1c/0x44)
>> [<c064f3f8>] (blkdev_fsync) from [<c064408c>] (do_fsync+0x3c/0x70)
>> [<c064408c>] (do_fsync) from [<c0400374>] (__sys_trace_return+0x0/0x2c)
>> Exception stack(0xe376bfa8 to 0xe376bff0)
>> bfa0: 0003d2e0 b6f7b6f0 00000003 00046e40 00001000 00000000
>> bfc0: 0003d2e0 b6f7b6f0 00000000 00000076 00000000 00000000 befcbb20 befcbb28
>> bfe0: b6f4e060 befcbad8 b6f23e0c b6dc4a80
>> Code: e5927000 e0050391 e0871005 e5918018 (e5983000)
>>
>> Fixes: 61989a80fb3a ("staging: zsmalloc: zsmalloc memory allocation library")
>> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
>> ---
>> mm/zsmalloc.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
>> index c36fdff9a371..260bd48aacd0 100644
>> --- a/mm/zsmalloc.c
>> +++ b/mm/zsmalloc.c
>> @@ -40,6 +40,7 @@
>> #include <linux/string.h>
>> #include <linux/slab.h>
>> #include <linux/pgtable.h>
>> +#include <asm/sparsemem.h>
>
> asm/sparsemem.h is not available on some architectures.
> It's better to use linux/mmzone.h instead.
>
Hm, linux/mmzone.h only includes asm/sparsemem.h when CONFIG_SPARSEMEM
is enabled. However, on ARM at least I can have configurations without
CONFIG_SPARSEMEM and physical address extension on (e.g.
multi_v7_defconfig + CONFIG_LPAE + CONFIG_ZSMALLOC).
While sparsemem seems to be a good idea with LPAE it really seems not
required (see also https://lore.kernel.org/patchwork/patch/567589/).
There seem to be also other architectures which define MAX_PHYSMEM_BITS
only when SPARSEMEM is enabled, e.g.
arch/riscv/include/asm/sparsemem.h...
Not sure how to get out of this.. Maybe make ZSMALLOC dependent on
SPARSEMEM? It feels a bit silly restricting ZSMALLOC selection only due
to a compile time define...
--
Stefan
>> #include <asm/tlbflush.h>
>> #include <linux/cpumask.h>
>> #include <linux/cpu.h>
>> --
>> 2.29.1
>>
>>
