From: Peter Zijlstra <peterz@infradead.org>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Yair Podemsky <ypodemsk@redhat.com>,
ppandit@redhat.com, david@redhat.com, linux@armlinux.org.uk,
mpe@ellerman.id.au, npiggin@gmail.com,
christophe.leroy@csgroup.eu, hca@linux.ibm.com,
gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
keescook@chromium.org, paulmck@kernel.org, frederic@kernel.org,
will@kernel.org, ardb@kernel.org, samitolvanen@google.com,
juerg.haefliger@canonical.com, arnd@arndb.de,
rmk+kernel@armlinux.org.uk, geert+renesas@glider.be,
linus.walleij@linaro.org, akpm@linux-foundation.org,
sebastian.reichel@collabora.com, rppt@kernel.org,
aneesh.kumar@linux.ibm.com, x86@kernel.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
sparclinux@vger.kernel.org, linux-arch@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/2] send tlb_remove_table_smp_sync IPI only to necessary CPUs
Date: Mon, 3 Jul 2023 16:09:50 +0200 [thread overview]
Message-ID: <20230703140950.GL4253@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <ZJRC2s4sIuJ9V3A0@tpad>
On Thu, Jun 22, 2023 at 09:47:22AM -0300, Marcelo Tosatti wrote:
> > there's patches that cure the thp abuse of this.
>
> The other case where the IPI can happen is:
>
> CPU-0 CPU-1
>
> tlb_remove_table
> tlb_remove_table_sync_one
> IPI
> local_irq_disable
> gup_fast
> local_irq_enable
>
>
> So its not only the THP case.
(your CPU-1 thing is wholly irrelevant)
Well, I know, but this case *should* be exceedingly rare. Last time
around I asked why you all were tripping this, you pointed at the THP
case.
The THP case should be fixed along the lines of Jann's original patches.
If you can trip this at any significant rate, then we should probably
look at a better allocation scheme. It means you're really low on
memory.
next prev parent reply other threads:[~2023-07-03 14:10 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-20 14:46 Yair Podemsky
2023-06-20 14:46 ` [PATCH v2 1/2] arch: Introduce ARCH_HAS_CPUMASK_BITS Yair Podemsky
2023-06-20 14:46 ` [PATCH v2 2/2] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to MM CPUs Yair Podemsky
2023-06-21 17:42 ` Dave Hansen
2023-06-22 13:14 ` ypodemsk
2023-06-22 13:37 ` Dave Hansen
2023-06-26 14:36 ` ypodemsk
2023-06-26 15:23 ` Dave Hansen
2023-06-21 18:02 ` Nadav Amit
2023-06-22 13:57 ` ypodemsk
2023-06-23 3:38 ` Yang Shi
2023-07-03 13:57 ` Peter Zijlstra
2023-06-21 7:43 ` [PATCH v2 0/2] send tlb_remove_table_smp_sync IPI only to necessary CPUs Peter Zijlstra
2023-06-22 12:47 ` Marcelo Tosatti
2023-07-03 14:09 ` Peter Zijlstra [this message]
2023-06-22 13:11 ` ypodemsk
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