From: "Ard Biesheuvel" <ardb@kernel.org>
To: "Mike Rapoport" <rppt@kernel.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Cc: "Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
"Ingo Molnar" <mingo@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>,
"Thomas Gleixner" <tglx@kernel.org>,
linux-efi@vger.kernel.org, linux-mm@kvack.org,
stable@vger.kernel.org
Subject: Re: [PATCH v2] x86/efi: defer freeing of boot services memory
Date: Thu, 05 Mar 2026 12:11:12 +0100 [thread overview]
Message-ID: <7e4f6a4b-fe41-482d-a4cd-5a059e1626e6@app.fastmail.com> (raw)
In-Reply-To: <20260225065555.2471844-1-rppt@kernel.org>
On Wed, 25 Feb 2026, at 07:55, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
>
> efi_free_boot_services() frees memory occupied by EFI_BOOT_SERVICES_CODE
> and EFI_BOOT_SERVICES_DATA using memblock_free_late().
>
> There are two issue with that: memblock_free_late() should be used for
> memory allocated with memblock_alloc() while the memory reserved with
> memblock_reserve() should be freed with free_reserved_area().
>
> More acutely, with CONFIG_DEFERRED_STRUCT_PAGE_INIT=y
> efi_free_boot_services() is called before deferred initialization of the
> memory map is complete.
>
> Benjamin Herrenschmidt reports that this causes a leak of ~140MB of
> RAM on EC2 t3a.nano instances which only have 512MB or RAM.
>
Putting a fixes tag referencing a patch that dates back to 2011 doesn't seem that useful here. Is this really an issue that goes all the way back? Or did a later change trigger the actual leak?
prev parent reply other threads:[~2026-03-05 11:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-25 6:55 Mike Rapoport
2026-03-04 8:17 ` Mike Rapoport
2026-03-04 17:44 ` Dave Hansen
2026-03-04 17:45 ` Ard Biesheuvel
2026-03-05 11:11 ` Ard Biesheuvel [this message]
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