On 10/22/24 04:19, Hao Ge wrote: > > On 10/22/24 01:42, Suren Baghdasaryan wrote: >> On Sun, Oct 20, 2024 at 11:59 PM <xiaopeitux@xxxxxxxxxxx> wrote: >>> From: Pei Xiao <xiaopei01@xxxxxxxxxx> >>> >>> 'modprobe slub_kunit',will have a panic.The root cause is that >>> __kmalloc_cache_noprof was directly ,which resulted in no alloc_tag >>> being allocated.This caused current->alloc_tag to be null,leading to >>> a null pointer dereference in alloc_tag_ref_set. >> I think the root cause of this crash is the bug that is fixed by >> https://lore.kernel.org/all/20241020070819.307944-1-hao.ge@xxxxxxxxx/. >> Do you get this crash if you apply that fix? > Yes, this patch has resolved the panic issue. >>> Here is the log for the panic: >>> [ 74.779373][ T2158] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020 >>> [ 74.780130][ T2158] Mem abort info: >>> [ 74.780406][ T2158] ESR = 0x0000000096000004 >>> [ 74.780756][ T2158] EC = 0x25: DABT (current EL), IL = 32 bits >>> [ 74.781225][ T2158] SET = 0, FnV = 0 >>> [ 74.781529][ T2158] EA = 0, S1PTW = 0 >>> [ 74.781836][ T2158] FSC = 0x04: level 0 translation fault >>> [ 74.782288][ T2158] Data abort info: >>> [ 74.782577][ T2158] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 >>> [ 74.783068][ T2158] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 >>> [ 74.783533][ T2158] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 >>> [ 74.784010][ T2158] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000105f34000 >>> [ 74.784586][ T2158] [0000000000000020] pgd=0000000000000000, p4d=0000000000000000 >>> [ 74.785293][ T2158] Internal error: Oops: 0000000096000004 [#1] SMP >>> [ 74.785805][ T2158] Modules linked in: slub_kunit kunit ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ebtable_nat ebtable_broute ip6table_nat ip6table_mangle 4 >>> [ 74.790661][ T2158] CPU: 0 UID: 0 PID: 2158 Comm: kunit_try_catch Kdump: loaded Tainted: G W N 6.12.0-rc3+ #2 >>> [ 74.791535][ T2158] Tainted: [W]=WARN, [N]=TEST >>> [ 74.791889][ T2158] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 >>> [ 74.792479][ T2158] pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) >>> [ 74.793101][ T2158] pc : alloc_tagging_slab_alloc_hook+0x120/0x270 >>> [ 74.793607][ T2158] lr : alloc_tagging_slab_alloc_hook+0x120/0x270 >>> >>> [ 74.794095][ T2158] sp : ffff800084d33cd0 >>> [ 74.794418][ T2158] x29: ffff800084d33cd0 x28: 0000000000000000 x27: 0000000000000000 >>> [ 74.795095][ T2158] x26: 0000000000000000 x25: 0000000000000012 x24: ffff80007b30e314 >>> [ 74.795822][ T2158] x23: ffff000390ff6f10 x22: 0000000000000000 x21: 0000000000000088 >>> [ 74.796555][ T2158] x20: ffff000390285840 x19: fffffd7fc3ef7830 x18: ffffffffffffffff >>> [ 74.797283][ T2158] x17: ffff8000800e63b4 x16: ffff80007b33afc4 x15: ffff800081654c00 >>> [ 74.798011][ T2158] x14: 0000000000000000 x13: 205d383531325420 x12: 5b5d383734363537 >>> [ 74.798744][ T2158] x11: ffff800084d337e0 x10: 000000000000005d x9 : 00000000ffffffd0 >>> [ 74.799476][ T2158] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008219d188 x6 : c0000000ffff7fff >>> [ 74.800206][ T2158] x5 : ffff0003fdbc9208 x4 : ffff800081edd188 x3 : 0000000000000001 >>> [ 74.800932][ T2158] x2 : 0beaa6dee1ac5a00 x1 : 0beaa6dee1ac5a00 x0 : ffff80037c2cb000 >>> [ 74.801656][ T2158] Call trace: >>> [ 74.801954][ T2158] alloc_tagging_slab_alloc_hook+0x120/0x270 >>> [ 74.802494][ T2158] __kmalloc_cache_noprof+0x148/0x33c >>> [ 74.802976][ T2158] test_kmalloc_redzone_access+0x4c/0x104 [slub_kunit] >>> [ 74.803607][ T2158] kunit_try_run_case+0x70/0x17c [kunit] >>> [ 74.804124][ T2158] kunit_generic_run_threadfn_adapter+0x2c/0x4c [kunit] >>> [ 74.804768][ T2158] kthread+0x10c/0x118 >>> [ 74.805141][ T2158] ret_from_fork+0x10/0x20 >>> [ 74.805540][ T2158] Code: b9400a80 11000400 b9000a80 97ffd858 (f94012d3) >>> [ 74.806176][ T2158] SMP: stopping secondary CPUs >>> [ 74.808130][ T2158] Starting crashdump kernel... >>> >> CC'ing Vlastimil. >> This patch essentially reverts Vlastimil's "mm, slab: don't wrap >> internal functions with alloc_hooks()" change. Please check why that >> change was needed before proceeding. >> If this change is indeed needed, please add: > > Hi Suren and Vlastimil > > In fact, besides the panic, there is also a warning here due to directly > invoking__kmalloc_cache_noprof > > Regarding this, do you have any suggestions? > > [58162.947016] WARNING: CPU: 2 PID: 6210 at > ./include/linux/alloc_tag.h:125 alloc_tagging_slab_alloc_hook+0x268/0x27c > [58162.957721] Call trace: > [58162.957919] alloc_tagging_slab_alloc_hook+0x268/0x27c > [58162.958286] __kmalloc_cache_noprof+0x14c/0x344 > [58162.958615] test_kmalloc_redzone_access+0x50/0x10c [slub_kunit] > [58162.959045] kunit_try_run_case+0x74/0x184 [kunit] > [58162.959401] kunit_generic_run_threadfn_adapter+0x2c/0x4c [kunit] > [58162.959841] kthread+0x10c/0x118 > [58162.960093] ret_from_fork+0x10/0x20 > [58162.960363] ---[ end trace 0000000000000000 ]--- I see. The kunit test is the only user of __kmalloc_cache_noprof outside of kmalloc() itself so it's not worth defining again a wrapper for everyone, how about just wrapping the two callsites? --- a/lib/slub_kunit.c +++ b/lib/slub_kunit.c @@ -141,7 +141,7 @@ static void test_kmalloc_redzone_access(struct kunit *test) { struct kmem_cache *s = test_kmem_cache_create("TestSlub_RZ_kmalloc", 32, SLAB_KMALLOC|SLAB_STORE_USER|SLAB_RED_ZONE); - u8 *p = __kmalloc_cache_noprof(s, GFP_KERNEL, 18); + u8 *p = alloc_hooks(__kmalloc_cache_noprof(s, GFP_KERNEL, 18)); kasan_disable_current(); @@ -199,7 +199,7 @@ static void test_krealloc_redzone_zeroing(struct kunit *test) struct kmem_cache *s = test_kmem_cache_create("TestSlub_krealloc", 64, SLAB_KMALLOC|SLAB_STORE_USER|SLAB_RED_ZONE); - p = __kmalloc_cache_noprof(s, GFP_KERNEL, 48); + p = alloc_hooks(__kmalloc_cache_noprof(s, GFP_KERNEL, 48)); memset(p, 0xff, 48); kasan_disable_current();
