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Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , Xu Xin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 9b9s6zy6bpyyfqghrhcyhod9womqa97k X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 536FC1C0002 X-HE-Tag: 1747710889-441968 X-HE-Meta: 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 aT6Gsq3f Fob7zSB0sDxvFZTnxSR4pBzsBFP7Z4MPj9obKjp28lzBgNQxad/LMqHLwTyo6IWq3IPXR8TvBJQhCZvRlup4Jnr9HCRao27PTA/7ccGTS1h+TmPmD1hUIyv2AQsoIgrpww76wX9Urkd5ltXWFHHs/Tx2yFZAH7S8f7yJXYZeoOPsLWF5YW6yVs2X96qfiL75n1hZasADOBF1sdaGKy0oJZ5aKVQdMFlT+jd/WVYbv4wdjhcztwOyxRD574A== 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 2025/5/19 16:51, Lorenzo Stoakes wrote: > In subsequent commits we are going to determine KSM eligibility prior to a > VMA being constructed, at which point we will of course not yet have access > to a VMA pointer. > > It is trivial to boil down the check logic to be parameterised on > mm_struct, file and VMA flags, so do so. > > As a part of this change, additionally expose and use file_is_dax() to > determine whether a file is being mapped under a DAX inode. > > Signed-off-by: Lorenzo Stoakes Looks good to me. Reviewed-by: Chengming Zhou Thanks! > --- > include/linux/fs.h | 7 ++++++- > mm/ksm.c | 32 ++++++++++++++++++++------------ > 2 files changed, 26 insertions(+), 13 deletions(-) > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 09c8495dacdb..e1397e2b55ea 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -3691,9 +3691,14 @@ void setattr_copy(struct mnt_idmap *, struct inode *inode, > > extern int file_update_time(struct file *file); > > +static inline bool file_is_dax(const struct file *file) > +{ > + return file && IS_DAX(file->f_mapping->host); > +} > + > static inline bool vma_is_dax(const struct vm_area_struct *vma) > { > - return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host); > + return file_is_dax(vma->vm_file); > } > > static inline bool vma_is_fsdax(struct vm_area_struct *vma) > diff --git a/mm/ksm.c b/mm/ksm.c > index 8583fb91ef13..08d486f188ff 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -677,28 +677,33 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr, bool lock_v > return (ret & VM_FAULT_OOM) ? -ENOMEM : 0; > } > > -static bool vma_ksm_compatible(struct vm_area_struct *vma) > +static bool ksm_compatible(const struct file *file, vm_flags_t vm_flags) > { > - if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE | VM_PFNMAP | > - VM_IO | VM_DONTEXPAND | VM_HUGETLB | > - VM_MIXEDMAP| VM_DROPPABLE)) > + if (vm_flags & (VM_SHARED | VM_MAYSHARE | VM_PFNMAP | > + VM_IO | VM_DONTEXPAND | VM_HUGETLB | > + VM_MIXEDMAP | VM_DROPPABLE)) > return false; /* just ignore the advice */ > > - if (vma_is_dax(vma)) > + if (file_is_dax(file)) > return false; > > #ifdef VM_SAO > - if (vma->vm_flags & VM_SAO) > + if (vm_flags & VM_SAO) > return false; > #endif > #ifdef VM_SPARC_ADI > - if (vma->vm_flags & VM_SPARC_ADI) > + if (vm_flags & VM_SPARC_ADI) > return false; > #endif > > return true; > } > > +static bool vma_ksm_compatible(struct vm_area_struct *vma) > +{ > + return ksm_compatible(vma->vm_file, vma->vm_flags); > +} > + > static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm, > unsigned long addr) > { > @@ -2696,14 +2701,17 @@ static int ksm_scan_thread(void *nothing) > return 0; > } > > -static void __ksm_add_vma(struct vm_area_struct *vma) > +static bool __ksm_should_add_vma(const struct file *file, vm_flags_t vm_flags) > { > - unsigned long vm_flags = vma->vm_flags; > - > if (vm_flags & VM_MERGEABLE) > - return; > + return false; > + > + return ksm_compatible(file, vm_flags); > +} > > - if (vma_ksm_compatible(vma)) > +static void __ksm_add_vma(struct vm_area_struct *vma) > +{ > + if (__ksm_should_add_vma(vma->vm_file, vma->vm_flags)) > vm_flags_set(vma, VM_MERGEABLE); > } >