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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=L1ipuc6pUg//TJm2iPvJ8j4e8NZzKbVkfx4X1O65glkyl1Z6AzAdvwnb9H9muTdJO yIY6NujGnMcYEdyOgxBHRN6ZdFko2nQQ03RgGjxLf8sfQD0J/IMOFAieH7m5C84m1a DYnT2j6Lc7v4DOn1UajCixH0dkmX1SKs8MWOtFHM= Message-ID: Date: Mon, 29 Jun 2026 12:17:07 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 6/6] mm/vmalloc: align vm_area so vmap() can batch mappings To: Wen Jiang , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, urezki@gmail.com Cc: baohua@kernel.org, Xueyuan.chen21@gmail.com, rppt@kernel.org, david@kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, ajd@linux.ibm.com, linux-kernel@vger.kernel.org, jiangwen6@xiaomi.com, shanghaoqiang@xiaomi.com References: <20260618084726.1070022-1-jiangwen6@xiaomi.com> <20260618084726.1070022-7-jiangwen6@xiaomi.com> Content-Language: en-US From: Dev Jain In-Reply-To: <20260618084726.1070022-7-jiangwen6@xiaomi.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: A3A3520002 X-Rspam-User: X-Stat-Signature: curze3rk7g1rin5htyu5k6p55dbbrye8 X-HE-Tag: 1782715635-284177 X-HE-Meta: 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 gWxC7PmW 2k+PHWrB1wUZ1+4Syja+U0CUerHkquFPIIfWEcinLuDNfRO7pepCLfW9w/D7CbotfgfWk7kSisw2PtBEE9Ug40hPxen4NGVBNqCGxq6J4NlTAgZSEwJPU+2BTxJWR56cTxji1trtBsbKJiRaI0h8cFdSjqkmyOLhNjwmLEJFustVIjk/j/7XsIrW91510Dsovci8p3O+MAayRb1ve4MXumh2Ex2USemq7TTW+IDzGY/j8HFtsJDJEYjyu/YLKM6o+x85Bw04eXJqRWUAtOXarfib8kTj+i4o+7crhMkXgUkAS/lw/psFQOrtYThuu8HEUBZHWMhZPhByEiVSzyPQvZI2dBweqsxL07npTqXSuIkfwGg89FGtK5oeGLv2vZzicSws+QhH0qFkPrHOe6zHJDSLIHAFuQMY/1M77Ykr2eYeKQgG/11HDM7IVsA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 18/06/26 2:17 pm, Wen Jiang wrote: > From: "Barry Song (Xiaomi)" > > Try to align the vmap virtual address to PMD_SHIFT or a > larger PTE mapping size hinted by the architecture, so > contiguous pages can be batch-mapped when setting PMD or > PTE entries. > > Add __get_vm_area_node_aligned_caller() as a wrapper over > __get_vm_area_node() to simplify repeated calls with fixed > arguments. > > Signed-off-by: Barry Song (Xiaomi) > Signed-off-by: Wen Jiang > Tested-by: Xueyuan Chen > --- > mm/vmalloc.c | 37 ++++++++++++++++++++++++++++++++++++- > 1 file changed, 36 insertions(+), 1 deletion(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index fffb885cb2158..bc9fa93e2bdc6 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3628,6 +3628,41 @@ static int vmap_batched(unsigned long addr, unsigned long end, > return err; > } > > +static struct vm_struct *__get_vm_area_node_aligned_caller(unsigned long size, > + unsigned long align, unsigned long flags, const void *caller) There are 3 similar functions below __get_vm_area_node: they are __get_vm_area_caller, get_vm_area and get_vm_area_caller. You can put this one just below them. > +{ > + return __get_vm_area_node(size, align, PAGE_SHIFT, flags, > + VMALLOC_START, VMALLOC_END, > + NUMA_NO_NODE, GFP_KERNEL, caller); > +} > + > +static struct vm_struct *vmap_get_aligned_vm_area(unsigned long size, > + unsigned long flags, const void *caller) > +{ > + struct vm_struct *vm_area; > + unsigned int shift; > + > + /* Try PMD alignment for large sizes */ This comment feels excessive. Can remove it. > + if (size >= PMD_SIZE) { Need an arch_vmap_pmd_supported() check here. > + vm_area = __get_vm_area_node_aligned_caller(size, PMD_SIZE, > + flags, caller); > + if (vm_area) > + return vm_area; > + } > + > + /* Try CONT_PTE alignment */ Comment feels excessive, and again no need to mention arm64 specific stuff here. Just remove it. > + shift = arch_vmap_pte_supported_shift(size); > + if (shift > PAGE_SHIFT) { > + vm_area = __get_vm_area_node_aligned_caller(size, 1UL << shift, > + flags, caller); > + if (vm_area) > + return vm_area; > + } > + > + /* Fall back to page alignment */ This comment can also be dropped, but I am fine either way. > + return __get_vm_area_node_aligned_caller(size, PAGE_SIZE, flags, caller); > +} > + > /** > * vmap - map an array of pages into virtually contiguous space > * @pages: array of page pointers > @@ -3666,7 +3701,7 @@ void *vmap(struct page **pages, unsigned int count, > return NULL; > > size = (unsigned long)count << PAGE_SHIFT; > - area = get_vm_area_caller(size, flags, __builtin_return_address(0)); > + area = vmap_get_aligned_vm_area(size, flags, __builtin_return_address(0)); So the effect is that now we search for an aligned vm_struct unconditionally. Better to mention in the commit message that we do not expect any significant overhead for this. > if (!area) > return NULL; >