From: David Hildenbrand <david@redhat.com>
To: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>,
linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org, Sourabh Jain <sourabhjain@linux.ibm.com>,
Hari Bathini <hbathini@linux.ibm.com>, Zi Yan <ziy@nvidia.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
"Aneesh Kumar K . V" <aneesh.kumar@kernel.org>,
Donet Tom <donettom@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
Sachin P Bappalige <sachinpb@linux.ibm.com>
Subject: Re: [RFC 1/2] cma: Fix CMA_MIN_ALIGNMENT_BYTES during early_init
Date: Tue, 8 Oct 2024 15:50:46 +0200 [thread overview]
Message-ID: <83eb128e-4f06-4725-a843-a4563f246a44@redhat.com> (raw)
In-Reply-To: <c1e66d3e69c8d90988c02b84c79db5d9dd93f053.1728386179.git.ritesh.list@gmail.com>
On 08.10.24 15:27, Ritesh Harjani (IBM) wrote:
> During early init CMA_MIN_ALIGNMENT_BYTES can be PAGE_SIZE,
> since pageblock_order is still zero and it gets initialized
> later during paging_init() e.g.
> paging_init() -> free_area_init() -> set_pageblock_order().
>
> One such use case is -
> early_setup() -> early_init_devtree() -> fadump_reserve_mem()
>
> This causes CMA memory alignment check to be bypassed in
> cma_init_reserved_mem(). Then later cma_activate_area() can hit
> a VM_BUG_ON_PAGE(pfn & ((1 << order) - 1)) if the reserved memory
> area was not pageblock_order aligned.
>
> Instead of fixing it locally for fadump case on PowerPC, I believe
> this should be fixed for CMA_MIN_ALIGNMENT_BYTES.
I think we should add a way to catch the usage of
CMA_MIN_ALIGNMENT_BYTES before it actually has meaning (before
pageblock_order was set) and fix the PowerPC usage by reshuffling the
code accordingly.
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2024-10-08 13:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-08 13:27 [RFC 1/2] cma: Fix CMA_MIN_ALIGNMENT_BYTES during early_init Ritesh Harjani (IBM)
2024-10-08 13:27 ` [RFC 2/2] fadump: Make fadump reserve_dump_area_start CMA aligned in case of holes Ritesh Harjani (IBM)
2024-10-08 13:50 ` David Hildenbrand [this message]
2024-10-10 3:19 ` [RFC 1/2] cma: Fix CMA_MIN_ALIGNMENT_BYTES during early_init Ritesh Harjani
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