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From: Dave Hansen <dave.hansen@intel.com>
To: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Hildenbrand <david@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>,
	"Liam R . Howlett" <liam@infradead.org>,
	Vlastimil Babka <vbabka@kernel.org>,
	Mike Rapoport <rppt@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>,
	Vishal Moola <vishal.moola@gmail.com>,
	Ingo Molnar <mingo@kernel.org>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	x86@kernel.org, linux-mm@kvack.org, regressions@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm: don't schedule deferred kernel page table freeing while booting
Date: Thu, 24 Sep 2026 10:57:08 -0700	[thread overview]
Message-ID: <6a0c2fd9-b2e1-40d2-b7a1-ba93cb3c53a3@intel.com> (raw)
In-Reply-To: <20260924092307.22813-1-mikhail.v.gavrilov@gmail.com>

On 9/24/26 02:23, Mikhail Gavrilov wrote:
> Keep putting the table on the list, but don't schedule the work while
> the system is still booting.  The next kernel page table freed after
> boot schedules it, and the work then frees the early table too, after
> the same IOMMU flush as any other.  If no kernel page table is freed
> after boot, the ones freed during boot stay on the list.

There seems to be an awful lot of chit chat about how and when the
boot-time tables might get freed. Like:

> So on this box the early tables wait until the first module is
> loaded, and no separate drain is needed.
Wouldn't a "separate drain" be all of 5 lines of code?

/* Take care of deferred freeing from boot: */
static __init int free_boot_kernel_pgtables(void)
{
	schedule_work(&kernel_pgtable_work.work);
}
late_initcall(free_boot_kernel_pgtables);

Then we don't have to reason about it at all.

  parent reply	other threads:[~2026-09-24 17:57 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-24  9:23 Mikhail Gavrilov
2026-09-24  9:31 ` Lorenzo Stoakes (ARM)
2026-09-24  9:39   ` Mikhail Gavrilov
2026-09-24 16:19 ` Mike Rapoport
2026-09-24 17:57 ` Dave Hansen [this message]
2026-09-24 18:47   ` David Hildenbrand (Arm)

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