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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4526e056138sm133067405e9.5.2025.06.10.00.08.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 10 Jun 2025 00:08:45 -0700 (PDT) Message-ID: <398d49f6-00c8-4bd8-ba30-62cbf0efee46@redhat.com> Date: Tue, 10 Jun 2025 09:08:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] mm: use folio_expected_ref_count() helper for reference counting To: Shivank Garg , mhiramat@kernel.org, oleg@redhat.com, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-mm@kvack.org References: <20250609170806.447302-2-shivankg@amd.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0F9B240009 X-Stat-Signature: ck7h7x67fujs67mqz7n1jz9iow4133sb X-Rspam-User: X-HE-Tag: 1749539329-675052 X-HE-Meta: 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 y+6llHU5 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09.06.25 19:08, Shivank Garg wrote: > Replace open-coded folio reference count calculations with the > folio_expected_ref_count() helper to improve code maintainability > and reduce duplication. > > No functional changes intended. > > Signed-off-by: Shivank Garg > --- > kernel/events/uprobes.c | 5 +++-- > mm/memfd.c | 4 ++-- > 2 files changed, 5 insertions(+), 4 deletions(-) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 4c965ba77f9f..c978c8c27340 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -434,10 +434,11 @@ static int __uprobe_write_opcode(struct vm_area_struct *vma, > /* > * When unregistering, we may only zap a PTE if uffd is disabled and > * there are no unexpected folio references ... > + * Expected refs: mappings + swapcache. > + * We hold one additional reference (+1). > */ > if (is_register || userfaultfd_missing(vma) || > - (folio_ref_count(folio) != folio_mapcount(folio) + 1 + > - folio_test_swapcache(folio) * folio_nr_pages(folio))) > + (folio_ref_count(folio) != folio_expected_ref_count(folio) + 1)) > goto remap; > With the comment removed (the caller holds a reference from GUP) or simplified ("Caller holds an additional folio reference.") Acked-by: David Hildenbrand -- Cheers, David / dhildenb