The patch titled
Subject: frontswap: skip frontswap_ops init if zswap init failed.
has been added to the -mm mm-unstable branch. Its filename is
frontswap-skip-frontswap_ops-init-if-zswap-init-failed.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/frontswap-skip-frontswap_ops-init-if-zswap-init-failed.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Liu Shixin <liushixin2@xxxxxxxxxx>
Subject: frontswap: skip frontswap_ops init if zswap init failed.
Date: Sat, 27 Aug 2022 18:45:56 +0800
Patch series "Delay the initializaton of zswap", v3.
In the initialization of zswap, about 18MB memory will be allocated for
zswap_pool. Since not all users use zswap, the memory may be wasted.
Save the memory for these users by delaying the initialization of zswap to
first enablement.
This patch (of 5):
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 ]---
Link: https://lkml.kernel.org/r/20220827104600.1813214-1-liushixin2@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20220827104600.1813214-2-liushixin2@xxxxxxxxxx
Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Seth Jennings <sjenning@xxxxxxxxxx>
Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/frontswap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/frontswap.c~frontswap-skip-frontswap_ops-init-if-zswap-init-failed
+++ a/mm/frontswap.c
@@ -125,7 +125,8 @@ void frontswap_init(unsigned type, unsig
* 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,
_
Patches currently in -mm which might be from liushixin2@xxxxxxxxxx are
bootmem-remove-the-vmemmap-pages-from-kmemleak-in-put_page_bootmem.patch
frontswap-skip-frontswap_ops-init-if-zswap-init-failed.patch
frontswap-invoke-ops-init-for-online-swap-device-in-frontswap_register_ops.patch
mm-zswap-replace-zswap_init_started-failed-with-zswap_init_state.patch
mm-zswap-delay-the-initializaton-of-zswap-until-the-first-enablement.patch
mm-zswap-skip-confusing-print-info.patch
