On 11/7/20 7:22 AM, 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>
BTW, I can confirm on behalf of a colleague here that this patch fixes
zsmalloc on a 32-bit platform with 4GB of DRAM and with a 3GB user/1GB
kernel split. Thanks!
--
Florian
