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From: Shakeel Butt To: SeongJae Park Cc: "Liam R. Howlett" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Vlastimil Babka , kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 02/16] mm/madvise: split out populate behavior check logic Message-ID: References: <20250305181611.54484-1-sj@kernel.org> <20250305181611.54484-3-sj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250305181611.54484-3-sj@kernel.org> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: E7096A001E X-Stat-Signature: mr1ze4ace7n9cqmy8a6199ixr3a3giqu X-HE-Tag: 1741206786-404101 X-HE-Meta: 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 CUopLF0Z QhqXh40efbux2PZ8pWPAp2LUIP7X0dz6tUl2ynVRGR65xfuwll8E+e6MyEMUgQjOK8a9YKixqUo7W+RxdAki84gCe5cvg0XdIDR2uGcV7U4heym07SPzxk5njeYPdlcKXvYfnHXb0aSwHD4+J9bJnwCpQKbbZiSJzYhgKgfAFevv/xoQP783U2QtnazCM4GikCGUPez0XAbTuvQ4= 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 Wed, Mar 05, 2025 at 10:15:57AM -0800, SeongJae Park wrote: > madvise_do_behavior() has a long open-coded 'behavior' check for > MADV_POPULATE_{READ,WRITE}. It adds multiple layers[1] and make the > code arguably take longer time to read. Like is_memory_failure(), split > out the check to a separate function. This is not technically removing > the additional layer but discourage further extending the switch-case. > Also it makes madvise_do_behavior() code shorter and therefore easier to > read. > > [1] https://lore.kernel.org/bd6d0bf1-c79e-46bd-a810-9791efb9ad73@lucifer.local > > Signed-off-by: SeongJae Park > --- > mm/madvise.c | 20 +++++++++++++------- > 1 file changed, 13 insertions(+), 7 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index dbc8fec05cc6..4a91590656dc 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1633,6 +1633,17 @@ static bool is_valid_madvise(unsigned long start, size_t len_in, int behavior) > return true; > } > > +static bool is_memory_populate(int behavior) No strong opinion on this patch but if you want to keep it, the above name feels weird. How about either is_madvise_populate() or is_populate_memory()? > +{ > + switch (behavior) { > + case MADV_POPULATE_READ: > + case MADV_POPULATE_WRITE: > + return true; > + default: > + return false; > + } > +} > + > static int madvise_do_behavior(struct mm_struct *mm, > unsigned long start, size_t len_in, size_t len, int behavior) > { > @@ -1646,16 +1657,11 @@ static int madvise_do_behavior(struct mm_struct *mm, > end = start + len; > > blk_start_plug(&plug); > - switch (behavior) { > - case MADV_POPULATE_READ: > - case MADV_POPULATE_WRITE: > + if (is_memory_populate(behavior)) > error = madvise_populate(mm, start, end, behavior); > - break; > - default: > + else > error = madvise_walk_vmas(mm, start, end, behavior, > madvise_vma_behavior); > - break; > - } > blk_finish_plug(&plug); > return error; > } > -- > 2.39.5