From: Will Deacon <will@kernel.org>
To: Shanker Donthineni <sdonthineni@nvidia.com>
Cc: James Morse <james.morse@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org,
Rohit Mathew <Rohit.Mathew@arm.com>,
Vikram Sethi <vsethi@nvidia.com>
Subject: Re: [PATCH v2 1/1] drivers/perf: Fix kernel panic due to the invalid mon_ctx pointer
Date: Fri, 27 Oct 2023 11:27:07 +0100 [thread overview]
Message-ID: <20231027102707.GA7899@willie-the-truck> (raw)
In-Reply-To: <20231026233443.3493667-1-sdonthineni@nvidia.com>
On Thu, Oct 26, 2023 at 06:34:43PM -0500, Shanker Donthineni wrote:
> The return pointer from the resctrl_arch_mon_ctx_alloc_no_wait() function
> is saved in a 32-bit variable 'hwc->idx' which results in the loss of
> the upper 32 bits. This, in turn, triggers a kernel panic when attempting
> to access a corrupted pointer.
>
> Use 'event->pmu_private' instead of 'hwc->idx' to resolve the issue.
>
> Another reason contributing to the problem due to continuous 'error irq'
> messages. The resctrl_arch_mon_ctx_alloc_no_wait() function returns a valid
> PTR when it cannot allocate monitor resources, resulting in an incorrect
> MON_SEL configuration. To resolve this issue, return an ERR_PTR when monitor
> allocation fails
>
> dmesg:
> mpam: error irq from msc:0 'Monitor_Range', partid:228, pmg: 0, ris: 0
> mpam: error irq from msc:0 'Monitor_Range', partid:228, pmg: 0, ris: 0
> mpam: error irq from msc:0 'Monitor_Range', partid:228, pmg: 0, ris: 0
> ...
> mpam: error irq from msc:0 'Monitor_Range', partid:228, pmg: 0, ris: 0
>
> Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
> ---
> Changes in v2:
> -Use 'event->pmu_private' instead of 'hwc->idx' to keep monitor context
> -Return ERR_PTR if unable to allocate resource in resctrl_arch_mon_ctx_alloc_no_wait()
>
> drivers/perf/resctrl_pmu.c | 12 ++++++------
> drivers/platform/mpam/mpam_resctrl.c | 23 ++++++++++++++++-------
I can't see these files upstream or in linux-next, so please don't cc me on
changes to them until they've landed. My inbox is bad enough as it is!
Thanks,
Will
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prev parent reply other threads:[~2023-10-27 10:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-26 23:34 [PATCH v2 1/1] drivers/perf: Fix kernel panic due to the invalid mon_ctx pointer Shanker Donthineni
2023-10-27 10:27 ` Will Deacon [this message]
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