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smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD1BBC4CEEB; Thu, 21 Aug 2025 12:52:07 +0000 (UTC) Message-ID: Date: Thu, 21 Aug 2025 14:52:06 +0200 Precedence: bulk X-Mailing-List: sparclinux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Found it - was: Re: [PATCH] sparc64: fix hugetlb for sun4u To: John Paul Adrian Glaubitz , Anthony Yznaga , sparclinux@vger.kernel.org, davem@davemloft.net, andreas@gaisler.com Cc: linux-kernel@vger.kernel.org, agordeev@linux.ibm.com, will@kernel.org, ryan.roberts@arm.com, osalvador@suse.de, Meelis Roos , Rick Edgecombe References: <20250716012446.10357-1-anthony.yznaga@oracle.com> <35f5ec4eda8a7dbeeb7df9ec0be5c0b062c509f7.camel@physik.fu-berlin.de> <7e1e9aa5-0529-4fb5-84fb-557b5cc1cd50@oracle.com> <38f4469f48e6d36fa92b445c8ecef7a440be43e6.camel@physik.fu-berlin.de> <2bcb018c8b237f7ab2356f4459e14ae81a6fec8b.camel@physik.fu-berlin.de> <2daaa0648e9bcca42bf7a76d90580725f44fb4bc.camel@physik.fu-berlin.de> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit >> >> @Anthony: Can you see any suspicious in the disassembled code that Meelis (CC'ed) posted? > > OK, bisecting has lead me to the following commit: CCing Rick. Hm, but that's bpf-only code. Are you sure that it's this exact commit or rather .... > > d53d2f78ceadba081fc7785570798c3c8d50a718 is the first bad commit > commit d53d2f78ceadba081fc7785570798c3c8d50a718 (HEAD) > Author: Rick Edgecombe > Date: Thu Apr 25 17:11:38 2019 -0700 > > bpf: Use vmalloc special flag > > Use new flag VM_FLUSH_RESET_PERMS for handling freeing of special > permissioned memory in vmalloc and remove places where memory was set RW > before freeing which is no longer needed. Don't track if the memory is RO > anymore because it is now tracked in vmalloc. > > Signed-off-by: Rick Edgecombe > Signed-off-by: Peter Zijlstra (Intel) > Cc: > Cc: > Cc: > Cc: > Cc: > Cc: > Cc: > Cc: Alexei Starovoitov > Cc: Andy Lutomirski > Cc: Borislav Petkov > Cc: Daniel Borkmann > Cc: Dave Hansen > Cc: H. Peter Anvin > Cc: Linus Torvalds > Cc: Nadav Amit > Cc: Rik van Riel > Cc: Thomas Gleixner > Link: https://lkml.kernel.org/r/20190426001143.4983-19-namit@vmware.com > Signed-off-by: Ingo Molnar > > include/linux/filter.h | 17 +++-------------- > kernel/bpf/core.c | 1 - > 2 files changed, 3 insertions(+), 15 deletions(-) > > I assume it's also related to this change: ... this one? > > commit 868b104d7379e28013e9d48bdd2db25e0bdcf751 > Author: Rick Edgecombe > Date: Thu Apr 25 17:11:36 2019 -0700 > > mm/vmalloc: Add flag for freeing of special permsissions > > Add a new flag VM_FLUSH_RESET_PERMS, for enabling vfree operations to > immediately clear executable TLB entries before freeing pages, and handle > resetting permissions on the directmap. This flag is useful for any kind > of memory with elevated permissions, or where there can be related > permissions changes on the directmap. Today this is RO+X and RO memory. > > Although this enables directly vfreeing non-writeable memory now, > non-writable memory cannot be freed in an interrupt because the allocation > itself is used as a node on deferred free list. So when RO memory needs to > be freed in an interrupt the code doing the vfree needs to have its own > work queue, as was the case before the deferred vfree list was added to > vmalloc. > > For architectures with set_direct_map_ implementations this whole operation > can be done with one TLB flush when centralized like this. For others with > directmap permissions, currently only arm64, a backup method using > set_memory functions is used to reset the directmap. When arm64 adds > set_direct_map_ functions, this backup can be removed. > > When the TLB is flushed to both remove TLB entries for the vmalloc range > mapping and the direct map permissions, the lazy purge operation could be > done to try to save a TLB flush later. However today vm_unmap_aliases > could flush a TLB range that does not include the directmap. So a helper > is added with extra parameters that can allow both the vmalloc address and > the direct mapping to be flushed during this operation. The behavior of the > normal vm_unmap_aliases function is unchanged. > > Suggested-by: Dave Hansen > Suggested-by: Andy Lutomirski > Suggested-by: Will Deacon > Signed-off-by: Rick Edgecombe > Signed-off-by: Peter Zijlstra (Intel) > Cc: > Cc: > Cc: > Cc: > Cc: > Cc: > Cc: Borislav Petkov > Cc: H. Peter Anvin > Cc: Linus Torvalds > Cc: Nadav Amit > Cc: Rik van Riel > Cc: Thomas Gleixner > Link: https://lkml.kernel.org/r/20190426001143.4983-17-namit@vmware.com > Signed-off-by: Ingo Molnar > > Adrian > -- Cheers David / dhildenb