On Sat, Aug 27, 2022 at 12:12 PM Liu Shixin <liushixin2@xxxxxxxxxx> wrote: > > If zswap initial failed or has not been initial, frontswap_ops will be > NULL. In such situation, swap device would enable failed with following > stack trace: > > Unable to handle kernel access to user memory outside uaccess routines at virtual address 0000000000000000 > Mem abort info: > ESR = 0x0000000096000004 > EC = 0x25: DABT (current EL), IL = 32 bits > SET = 0, FnV = 0 > EA = 0, S1PTW = 0 > FSC = 0x04: level 0 translation fault > Data abort info: > ISV = 0, ISS = 0x00000004 > CM = 0, WnR = 0 > user pgtable: 4k pages, 48-bit VAs, pgdp=00000020a4fab000 > [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 > Internal error: Oops: 96000004 [#1] SMP > Modules linked in: zram fsl_dpaa2_eth pcs_lynx phylink ahci_qoriq crct10dif_ce ghash_ce sbsa_gwdt fsl_mc_dpio nvme lm90 nvme_core at803x xhci_plat_hcd rtc_fsl_ftm_alarm xgmac_mdio ahci_platform i2c_imx ip6_tables ip_tables fuse > Unloaded tainted modules: cppc_cpufreq():1 > CPU: 10 PID: 761 Comm: swapon Not tainted 6.0.0-rc2-00454-g22100432cf14 #1 > Hardware name: SolidRun Ltd. SolidRun CEX7 Platform, BIOS EDK II Jun 21 2022 > pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : frontswap_init+0x38/0x60 > lr : __do_sys_swapon+0x8a8/0x9f4 > sp : ffff80000969bcf0 > x29: ffff80000969bcf0 x28: ffff37bee0d8fc00 x27: ffff80000a7f5000 > x26: fffffcdefb971e80 x25: ffffaba797453b90 x24: 0000000000000064 > x23: ffff37c1f209d1a8 x22: ffff37bee880e000 x21: ffffaba797748560 > x20: ffff37bee0d8fce4 x19: ffffaba797748488 x18: 0000000000000014 > x17: 0000000030ec029a x16: ffffaba795a479b0 x15: 0000000000000000 > x14: 0000000000000000 x13: 0000000000000030 x12: 0000000000000001 > x11: ffff37c63c0aba18 x10: 0000000000000000 x9 : ffffaba7956b8c88 > x8 : ffff80000969bcd0 x7 : 0000000000000000 x6 : 0000000000000000 > x5 : 0000000000000001 x4 : 0000000000000000 x3 : ffffaba79730f000 > x2 : ffff37bee0d8fc00 x1 : 0000000000000000 x0 : 0000000000000000 > Call trace: > frontswap_init+0x38/0x60 > __do_sys_swapon+0x8a8/0x9f4 > __arm64_sys_swapon+0x28/0x3c > invoke_syscall+0x78/0x100 > el0_svc_common.constprop.0+0xd4/0xf4 > do_el0_svc+0x38/0x4c > el0_svc+0x34/0x10c > el0t_64_sync_handler+0x11c/0x150 > el0t_64_sync+0x190/0x194 > Code: d000e283 910003fd f9006c41 f946d461 (f9400021) > ---[ end trace 0000000000000000 ]--- > Well, this issue you are seeing is in fact introduced by the following patch: author Christoph Hellwig <hch@xxxxxx> 2022-01-21 22:15:10 -0800 frontswap: remove support for multiple ops So I would rather see that one reverted and fixed. Thanks, Vitaly > Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx> > Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx> > --- > mm/frontswap.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/frontswap.c b/mm/frontswap.c > index 1a97610308cb..620f95af81dd 100644 > --- a/mm/frontswap.c > +++ b/mm/frontswap.c > @@ -125,7 +125,8 @@ void frontswap_init(unsigned type, unsigned long *map) > * p->frontswap set to something valid to work properly. > */ > frontswap_map_set(sis, map); > - frontswap_ops->init(type); > + if (frontswap_ops) > + frontswap_ops->init(type); > } > > static bool __frontswap_test(struct swap_info_struct *sis, > -- > 2.25.1 >
