Messages in this thread | | | Date | Wed, 31 Jan 2024 20:28:19 +0800 | Subject | Re: Re: [linus:master] [sched/eevdf] 2227a957e1: BUG:kernel_NULL_pointer_dereference,address | From | Abel Wu <> |
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On 1/31/24 8:10 PM, Tiwei Bie Wrote: > On 1/30/24 6:13 PM, Abel Wu wrote: >> On 1/30/24 3:24 PM, kernel test robot Wrote: >>> >>> [ 512.079810][ T8305] BUG: kernel NULL pointer dereference, address: 0000002c >>> [ 512.080897][ T8305] #PF: supervisor read access in kernel mode >>> [ 512.081636][ T8305] #PF: error_code(0x0000) - not-present page >>> [ 512.082337][ T8305] *pde = 00000000 >>> [ 512.082829][ T8305] Oops: 0000 [#1] PREEMPT SMP >>> [ 512.083407][ T8305] CPU: 1 PID: 8305 Comm: watchdog Tainted: G W N 6.7.0-rc1-00006-g2227a957e1d5 #1 819e6d1a8b887f5f97adb4aed77d98b15504c836 >>> [ 512.084986][ T8305] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 >>> [ 512.086203][ T8305] EIP: set_next_entity (fair.c:?) >> >> There was actually a NULL-test in pick_eevdf() before this commit, >> but I removed it by intent as I found it impossible to be NULL after >> examining 'all' the cases. >> >> Also cc Tiwei who once proposed to add this check back. >> https://lore.kernel.org/all/20231208112100.18141-1-tiwei.btw@antgroup.com/ > > Thanks for cc'ing me. That's the case I worried about and why I thought > it might be worthwhile to add the sanity check back. I just sent out a > new version of the above patch with updated commit log and error message.
I assuming the real problem is why it *can* be NULL at first place. IMHO the NULL check with a fallback selection doesn't solve this, but it indeed avoids kernel panic which is absolutely important.
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