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[91.12.97.88]) by smtp.gmail.com with ESMTPSA id w6sm104904eje.107.2021.04.29.07.57.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Apr 2021 07:57:41 -0700 (PDT) Subject: Re: [PATCH v2 3/5] mm/huge_memory.c: add missing read-only THP checking in transparent_hugepage_enabled() To: Miaohe Lin , akpm@linux-foundation.org Cc: ziy@nvidia.com, william.kucharski@oracle.com, willy@infradead.org, yang.shi@linux.alibaba.com, aneesh.kumar@linux.ibm.com, rcampbell@nvidia.com, songliubraving@fb.com, kirill.shutemov@linux.intel.com, riel@surriel.com, hannes@cmpxchg.org, minchan@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20210429132648.305447-1-linmiaohe@huawei.com> <20210429132648.305447-4-linmiaohe@huawei.com> From: David Hildenbrand Organization: Red Hat Message-ID: <68c8c4a8-c4f8-83db-7326-dabeea74239c@redhat.com> Date: Thu, 29 Apr 2021 16:57:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210429132648.305447-4-linmiaohe@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29.04.21 15:26, Miaohe Lin wrote: > Since commit 99cb0dbd47a1 ("mm,thp: add read-only THP support for > (non-shmem) FS"), read-only THP file mapping is supported. But it > forgot to add checking for it in transparent_hugepage_enabled(). > To fix it, we add checking for read-only THP file mapping and also > introduce helper transhuge_vma_enabled() to check whether thp is > enabled for specified vma to reduce duplicated code. > > Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > Signed-off-by: Miaohe Lin > --- > include/linux/huge_mm.h | 21 +++++++++++++++++---- > mm/huge_memory.c | 6 ++++++ > mm/khugepaged.c | 4 +--- > mm/shmem.c | 3 +-- > 4 files changed, 25 insertions(+), 9 deletions(-) > > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > index 0a526f211fec..f460b74619fc 100644 > --- a/include/linux/huge_mm.h > +++ b/include/linux/huge_mm.h > @@ -115,6 +115,16 @@ extern struct kobj_attribute shmem_enabled_attr; > > extern unsigned long transparent_hugepage_flags; > > +static inline bool transhuge_vma_enabled(struct vm_area_struct *vma, > + unsigned long vm_flags) You're passing the vma already, why do you pass vma->vm_flags separately? It's sufficient to pass in the vma only. > +{ > + /* Explicitly disabled through madvise. */ > + if ((vm_flags & VM_NOHUGEPAGE) || > + test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) > + return false; > + return true; > +} > + > /* > * to be used on vmas which are known to support THP. > * Use transparent_hugepage_enabled otherwise > @@ -128,15 +138,12 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma) > if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX)) > return false; > > - if (vma->vm_flags & VM_NOHUGEPAGE) > + if (!transhuge_vma_enabled(vma, vma->vm_flags)) > return false; > > if (vma_is_temporary_stack(vma)) > return false; > > - if (test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) > - return false; > - > if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_FLAG)) > return true; > > @@ -362,6 +369,12 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, > return false; > } > > +static inline bool transhuge_vma_enabled(struct vm_area_struct *vma, > + unsigned long vm_flags) > +{ > + return false; > +} > + > static inline void prep_transhuge_page(struct page *page) {} > > static inline bool is_transparent_hugepage(struct page *page) > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 76ca1eb2a223..e24a96de2e37 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -68,12 +68,18 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma) > /* The addr is used to check if the vma size fits */ > unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; > > + if (!transhuge_vma_enabled(vma, vma->vm_flags)) > + return false; > if (!transhuge_vma_suitable(vma, addr)) > return false; > if (vma_is_anonymous(vma)) > return __transparent_hugepage_enabled(vma); > if (vma_is_shmem(vma)) > return shmem_huge_enabled(vma); > + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file && > + !inode_is_open_for_write(vma->vm_file->f_inode) && > + (vma->vm_flags & VM_EXEC)) > + return true; Nit: I'm really wondering why we have 3 different functions that sound like they are doing the same thing transparent_hugepage_enabled(vma) transhuge_vma_enabled() transhuge_vma_suitable() Which check belongs where? Does it really have to be that complicated? > > return false; > } > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 6c0185fdd815..d97b20fad6e8 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -442,9 +442,7 @@ static inline int khugepaged_test_exit(struct mm_struct *mm) > static bool hugepage_vma_check(struct vm_area_struct *vma, > unsigned long vm_flags) > { > - /* Explicitly disabled through madvise. */ > - if ((vm_flags & VM_NOHUGEPAGE) || > - test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) > + if (!transhuge_vma_enabled(vma, vm_flags)) > return false; > > /* Enabled via shmem mount options or sysfs settings. */ > diff --git a/mm/shmem.c b/mm/shmem.c > index a08cedefbfaa..1dcbec313c70 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -4032,8 +4032,7 @@ bool shmem_huge_enabled(struct vm_area_struct *vma) > loff_t i_size; > pgoff_t off; > > - if ((vma->vm_flags & VM_NOHUGEPAGE) || > - test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) > + if (!transhuge_vma_enabled(vma, vma->vm_flags)) > return false; > if (shmem_huge == SHMEM_HUGE_FORCE) > return true; > -- Thanks, David / dhildenb