Re: linux-next: not-present page at swap_vma_readahead()

From: Qian Cai
Date: Sun Jul 19 2020 - 23:54:18 EST

On Mon, Jul 20, 2020 at 03:32:59AM +0000, Huang, Ying wrote:
> Thanks! Can you try the dbg patch attached? That will print more debugging information when abnormal PTE pointer is detected.

Here with both of your patches applied,

[ 183.627876][ T3959] ra_info: 8, 3, 4, 00000000aabe3209
[ 183.633160][ T3959] i: 0, pte: 00000000aabe3209, faddr: 0
[ 183.638574][ T3959] ra_info: 8, 3, 4, 00000000aabe3209
[ 183.643787][ T3959] i: 1, pte: 0000000006e61f24, faddr: 0
[ 183.649189][ T3959] ra_info: 8, 3, 4, 00000000aabe3209
[ 183.654371][ T3959] i: 2, pte: 00000000ce16a68e, faddr: 0
[ 183.851372][ T3839] ra_info: 8, 3, 4, 0000000085efad17
[ 183.856550][ T3839] i: 0, pte: 0000000085efad17, faddr: 0
[ 183.862503][ T3839] ==================================================================
[ 183.870563][ T3839] BUG: KASAN: slab-out-of-bounds in swapin_readahead+0x840/0xd60
[ 183.878147][ T3839] Read of size 8 at addr ffff008919f1ffe8 by task trinity-c128/3839
[ 183.886001][ T3839] CPU: 9 PID: 3839 Comm: trinity-c128 Not tainted 5.8.0-rc5-next-20200717+ #2
[ 183.894710][ T3839] Hardware name: HPE Apollo 70 /C01_APACHE_MB , BIOS L50_5.13_1.11 06/18/2019
[ 183.905157][ T3839] Call trace:
[ 183.908314][ T3839] dump_backtrace+0x0/0x398
[ 183.912680][ T3839] show_stack+0x14/0x20
[ 183.916704][ T3839] dump_stack+0x140/0x1c8
[ 183.920910][ T3839] print_address_description.constprop.10+0x54/0x550
[ 183.927454][ T3839] kasan_report+0x134/0x1b8
[ 183.931833][ T3839] __asan_report_load8_noabort+0x2c/0x50
[ 183.937334][ T3839] swapin_readahead+0x840/0xd60
[ 183.942049][ T3839] do_swap_page+0xb1c/0x1a78
[ 183.946508][ T3839] handle_mm_fault+0xfd0/0x2c50
[ 183.948789][ T3754] ra_info: 8, 3, 4, 00000000d0b6ebd5
[ 183.951229][ T3839] do_page_fault+0x230/0x818
[ 183.956402][ T3754] i: 0, pte: 00000000d0b6ebd5, faddr: 0
[ 183.960896][ T3839] do_translation_fault+0x90/0xb0
[ 183.966330][ T3754] get_swap_device: Bad swap file entry 58025a5a5a5a5a5a
[ 183.971172][ T3839] do_mem_abort+0x64/0x180
[ 183.971192][ T3839] el0_sync_handler+0x2a0/0x410
[ 183.971207][ T3839] el0_sync+0x140/0x180
[ 183.977984][ T3754] ra_info: 8, 3, 4, 00000000d0b6ebd5
[ 183.977997][ T3754] i: 1, pte: 00000000530a7b17, faddr: 0
[ 183.982278][ T3839] Allocated by task 3699:
[ 183.982296][ T3839] kasan_save_stack+0x24/0x50
[ 183.982310][ T3839] __kasan_kmalloc.isra.10+0xc4/0xe0
[ 183.987003][ T3754] get_swap_device: Bad swap file entry 58025a5a5a5a5a5a
[ 183.987019][ T3754] ra_info: 8, 3, 4, 00000000d0b6ebd5
[ 183.991033][ T3839] kasan_slab_alloc+0x14/0x20
[ 183.991048][ T3839] slab_post_alloc_hook+0x58/0x5d0
[ 183.991064][ T3839] kmem_cache_alloc+0x19c/0x448
[ 183.996185][ T3754] i: 2, pte: 00000000031f0751, faddr: 0
[ 183.996200][ T3754] get_swap_device: Bad swap file entry 58025a5a5a5a5a5a
[ 184.001617][ T3839] create_object+0x58/0x960
[ 184.001639][ T3839] kmemleak_alloc+0x2c/0x38
[ 184.001657][ T3839] slab_post_alloc_hook+0x78/0x5d0
[ 184.025674][ T3830] ra_info: 8, 3, 4, 00000000d77f2b57
[ 184.027442][ T3839] kmem_cache_alloc+0x19c/0x448
[ 184.032002][ T3830] i: 0, pte: 0026 (3737) used g 184.047047][ T193][ T3839] co T3932] i: 0, pt59417][ T3932] i: 1, pte: 00000000e38ee039, faddr: 0
[ 184.059424][ T3932] ra_info: 8, 3, 4, 000000004ae69ce9
[ 184.059431][ T3932] i: 2, pte: 0000000035544c25, faddr: 0
[ 184.062563][ T3830] ra_info: 8, 3, 4, 00000000d77f2b57
[ 184.067511][ T3839] _do_fork+0x128/0x11f8
[ 184.072663][ T3830] i: 2, pte: 000000002f241b20, faddr: 0
[ 184.077369][ T3839] __do_sys_clone+0xac/0xd8
[ 184.110993][ T3997] ra_info: 8, 3, 4, 00000000d40684b7
[ 184.113421][ T3839] __arm64_sys_clone+0xa0/0xf8
[ 184.116524][ T3832] ra_info: 8, 3, 4, 00000000b572965a
[ 184.116534][ T3832] i: 0, pte: 00000000b572965a, faddr: 0
[ 184.116541][ T3832] ra_info: 8, 3, 4, 00000000b572965a
[ 184.116549][ T3832] i: 1, pte: 000000007c91cc64, faddr: 0
[ 184.116556][ T3832] ra_info: 8, 3, 4, 00000000b572965a
[ 184.116563][ T3832] i: 2, pte: 0000000024f944e4, faddr: 0
[ 184.118541][ T3997] i: 0, pte: 00000000d40684b7, faddr: 0
[ 184.118552][ T3997] ra_info: 8, 3, 4, 00000000d40684b7
[ 184.123956][ T3839] do_el0_svc+0x124/0x228
[ 184.123970][ T3839] el0_sync_handler+0x260/0x410
[ 184.123988][ T3839] el0_sync+0x140/0x180
[ 184.129119][ T3997] i: 1, pte: 0000000035d81ad0, faddr: 0
[ 184.134523][ T3839] The buggy address belongs to the object at ffff008919f1fd28
[ 184.134523][ T3839] which belongs to the cache kmemleak_object of size 368
[ 184.134535][ T3839] The buggy address is located 336 bytes to the right of
[ 184.134535][ T3839] 368-byte region [ffff008919f1fd28, ffff008919f1fe98)
[ 184.134542][ T3839] The buggy address belongs to the page:
[ 184.139678][ T3997] ra_info: 8, 3, 4, 00000000d40684b7
[ 184.142537][ T3814] ra_info: 8, 3, 4, 000000005be43c1f
[ 184.142548][ T3814] i: 0, pte: 000000005be43c1f, faddr: 0
[ 184.142555][ T3814] ra_info: 8, 3, 4, 000000005be43c1f
[ 184.142563][ T3814] i: 1, pte: 00000000f65153b4, faddr: 0
[ 184.142570][ T3814] ra_info: 8, 3, 4, 000000005be43c1f
[ 184.142577][ T3814] i: 2, pte: 0000000057432c18, faddr: 0
[ 184.145074][ T3839] page:00000000ab369b24 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8999f1
[ 184.145085][ T3839] flags: 0x7ffff800000200(slab)
[ 184.145097][ T3839] raw: 007ffff800000200 ffffffe0222685c8 ffffffe022268848 ffff000000322480
[ 184.145107][ T3839] raw: 0000000000000000 00000000005b005b 00000001ffffffff 0000000000000000
[ 184.145117][ T3839] page dumped because: kasan: bad access detected
[ 184.150249][ T3997] i: 2, pte: 0000000073c2aff0, faddr: 0
[ 184.154339][ T3839] Memory state around the buggy address:
[ 184.154347][ T3839] ffff008919f1fe80: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 184.154353][ T3839] ffff008919f1ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 184.154359][ T3839] >ffff008919f1ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 184.154366][ T3839] ^
[ 184.171894][ T3831] ra_info: 8, 3, 4, 00000000cf472abe
[ 184.173847][ T3839] ffff008919f20000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 184.178980][ T3831] i: 0, pte: 00000000cf472abe, faddr: 0
[ 184.184366][ T3839] ffff008919f20080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 184.184370][ T3839] ==================================================================
[ 184.184374][ T3839] Disabling lock debugging due to kernel taint
[ 184.184407][ T3839] get_swap_device: Bad swap file entry 58025a5a5a5a5a5a
[ 184.184415][ T3839] ra_info: 8, 3, 4, 0000000085efad17
[ 184.184420][ T3839] i: 1, pte: 00000000e75f3a33, faddr: 0
[ 184.184425][ T3839] get_swap_device: Bad swap file entry 58025a5a5a5a5a5a
[ 184.184445][ T3839] ra_info: 8, 3, 4, 0000000085efad17
[ 184.189580][ T3831] ra_info: 8, 3, 4, 00000000cf472abe
[ 184.194979][ T3839] i: 2, pte: 0000000076a382e8, faddr: 0
[ 184.194985][ T3839] get_swap_device: Bad swap file entry 58025a5a5a5a5a5a
[ 184.211498][ T3749] ra_info: 8, 3, 4, 000000001c9e06b8
[ 184.216321][ T3831] i: 1, pte: 00000000d0a5b31e, faddr: 0
[ 184.220485][ T3749] i: 0, pte: 000000001c9e06b8, faddr: 0
[ 184.220499][ T3749] ra_info: 8, 3, 4, 000000001c9e06b8
[ 184.225255][ T3831] ra_info: 8, 3, 4, 00000000cf472abe
[ 184.229226][ T3749] i: 1, pte: 000000003db42685, faddr: 0
[ 184.229238][ T3749] ra_info: 8, 3, 4, 000000001c9e06b8
[ 184.234658][ T3831] i: 2, pte: 000000002ff7eea4, faddr: 0
[ 184.248902][ T3749] i: 2, pte: 00000000f6f36e76, faddr: 0
[ 184.278122][ T3946] ra_info: 8, 3, 4, 0000000084aa2721
[ 184.279536][ T3720] trinity-c9 (3720) used greatest stack depth: 19440 bytes left
[ 184.283740][ T3946] i: 0, pte: 0000000084aa2721, faddr: 0
[ 184.283746][ T3946] ra_info: 8, 3, 4, 0000000084aa2721
[ 184.283751][ T3946] i: 1, pte: 00000000baf34b7a, faddr: 0
[ 184.283757][ T3946] ra_info: 8, 3, 4, 0000000084aa2721
[ 184.283762][ T3946] i: 2, pte: 0000000097da2f82, faddr: 0
[ 184.311719][ T3789] ra_info: 8, 3, 4, 00000000642615f8
[ 184.346297][ T3846] ra_info: 8, 3, 4, 00000000bfc701b4
[ 184.348700][ T3789] i: 0, pte: 00000000642615f8, faddr: 0
[ 184.357498][ T3846] i: 0, pte: 00000000bfc701b4, faddr: 0
[ 184.362168][ T3789] ra_info: 8, 3, 4, 00000000642615f8
[ 184.370076][ T3846] ra_info: 8, 3, 4, 00000000bfc701b4
[ 184.377998][ T3789] i: 1, pte: 000000002e399dd1, faddr: 0
[ 184.378008][ T3789] ra_info: 8, 3, 4, 00000000642615f8
[ 184.385317][ T3846] i: 1, pte: 000000002f17c4d4, faddr: 0
[ 184.385324][ T3846] ra_info: 8, 3, 4, 00000000bfc701b4
[ 184.390452][ T3789] i: 2, pte: 000000006b9fd0f4, faddr: 0
[ 184.398368][ T3846] i: 2, pte: 00000000b6695126, faddr: 0

>
> > From b6cad43ad3cf63d73e539e3eaadd4ec9d2744dc6 Mon Sep 17 00:00:00 2001
> > From: Huang Ying <ying.huang@xxxxxxxxx>
> > Date: Fri, 10 Jul 2020 17:27:45 +0800
> > Subject: [PATCH] dbg: Fix a logic hole in swap_ra_info()
> >
> > ---
> > mm/swap_state.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/swap_state.c b/mm/swap_state.c
> > index 05889e8e3c97..8481c15829b2 100644
> > --- a/mm/swap_state.c
> > +++ b/mm/swap_state.c
> > @@ -669,12 +669,11 @@ static void swap_ra_info(struct vm_fault *vmf,
> > pte_t *tpte;
> > #endif
> >
> > + ra_info->win = 1;
> > max_win = 1 << min_t(unsigned int, READ_ONCE(page_cluster),
> > SWAP_RA_ORDER_CEILING);
> > - if (max_win == 1) {
> > - ra_info->win = 1;
> > + if (max_win == 1)
> > return;
> > - }
> >
> > faddr = vmf->address;
> > orig_pte = pte = pte_offset_map(vmf->pmd, faddr);
> > --
> > 2.27.0
> >
>

> From 3ca7a9ba58541d8692d3f83cbded2ad17be23359 Mon Sep 17 00:00:00 2001
> From: Huang Ying <ying.huang@xxxxxxxxx>
> Date: Mon, 20 Jul 2020 11:29:38 +0800
> Subject: [PATCH] dbg: dump upon abnormal pte values
>
> ---
> mm/swap_state.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 05889e8e3c97..c1973136d035 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -756,6 +756,17 @@ static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
> blk_start_plug(&plug);
> for (i = 0, pte = ra_info.ptes; i < ra_info.nr_pte;
> i++, pte++) {
> + pte_t *tpte = pte_offset_map(vmf->pmd, vmf->address);
> +
> + if (((unsigned long)pte >> PAGE_SHIFT) !=
> + ((unsigned long)tpte >> PAGE_SHIFT)) {
> + pr_info("ra_info: %d, %d, %d, %p\n",
> + ra_info.win, ra_info.offset, ra_info.nr_pte,
> + ra_info.ptes);
> + pr_info("i: %d, pte: %p, faddr: %lx\n", i, pte,
> + vmf->address);
> + }
> + pte_unmap(tpte);
> pentry = *pte;
> if (pte_none(pentry))
> continue;
> --
> 2.27.0
>