From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Cc: "daniel@iogearbox.net" <daniel@iogearbox.net>,
"jeyu@kernel.org" <jeyu@kernel.org>,
"ast@kernel.org" <ast@kernel.org>,
"ard.biesheuvel@arm.com" <ard.biesheuvel@arm.com>,
"mroos@linux.ee" <mroos@linux.ee>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"namit@vmware.com" <namit@vmware.com>,
"luto@kernel.org" <luto@kernel.org>,
"Hansen, Dave" <dave.hansen@intel.com>
Subject: Re: [PATCH] vmalloc: Don't use flush flag when no exec perm
Date: Thu, 30 May 2019 03:55:11 +0000 [thread overview]
Message-ID: <89d6dee949e4418f0cca4cc6c4c9b526c1a5c497.camel@intel.com> (raw)
In-Reply-To: <20190529055104.6822-1-rick.p.edgecombe@intel.com>
On Tue, 2019-05-28 at 22:51 -0700, Rick Edgecombe wrote:
> The addition of VM_FLUSH_RESET_PERMS for BPF JIT allocations was
> bisected to prevent boot on an UltraSparc III machine. It was found
> that
> sometime shortly after the TLB flush this flag does on vfree of the
> BPF
> program, the machine hung. Further investigation showed that before
> any of
> the changes for this flag were introduced, with
> CONFIG_DEBUG_PAGEALLOC
> configured (which does a similar TLB flush of the vmalloc range on
> every vfree), this machine also hung shortly after the first vmalloc
> unmap/free.
>
> So the evidence points to there being some existing issue with the
> vmalloc TLB flushes, but it's still unknown exactly why these hangs
> are
> happening on sparc. It is also unknown when someone with this
> hardware
> could resolve this, and in the meantime using this flag on it turns a
> lurking behavior into something that prevents boot.
The sparc TLB flush issue has been bisected and is being worked on now,
so hopefully we won't need this patch:
https://marc.info/?l=linux-sparc&m=155915694304118&w=2
next prev parent reply other threads:[~2019-05-30 3:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-29 5:51 Rick Edgecombe
2019-05-30 3:55 ` Edgecombe, Rick P [this message]
2019-05-30 7:44 ` Meelis Roos
2019-05-31 4:36 ` Edgecombe, Rick P
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