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User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Message-ID-Hash: X2BR5HG7LDNIAI4BNXWAXPKCOOFDTVNW X-Message-ID-Hash: X2BR5HG7LDNIAI4BNXWAXPKCOOFDTVNW X-MailFrom: mpatocka@redhat.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Linus Torvalds , Jan Kara , Dave Chinner , Jann Horn , Christoph Hellwig , Oleg Nesterov , Kirill Shutemov , Theodore Ts'o , Andrea Arcangeli , Matthew Wilcox , Andrew Morton , Linux-MM , Linux Kernel Mailing List , linux-nvdimm , Ext4 Developers List , linux-xfs X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: TEXT/PLAIN; charset="us-ascii" Content-Transfer-Encoding: 7bit When running in a dax mode, if the user maps a page with MAP_PRIVATE and PROT_WRITE, the xfs filesystem would incorrectly update ctime and mtime when the user hits a COW fault. This breaks building of the Linux kernel. How to reproduce: 1. extract the Linux kernel tree on dax-mounted xfs filesystem 2. run make clean 3. run make -j12 4. run make -j12 - at step 4, make would incorrectly rebuild the whole kernel (although it was already built in step 3). The reason for the breakage is that almost all object files depend on objtool. When we run objtool, it takes COW page fault on its .data section, and these faults will incorrectly update the timestamp of the objtool binary. The updated timestamp causes make to rebuild the whole tree. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org --- fs/xfs/xfs_file.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) Index: linux-2.6/fs/xfs/xfs_file.c =================================================================== --- linux-2.6.orig/fs/xfs/xfs_file.c 2020-09-05 18:48:54.000000000 +0200 +++ linux-2.6/fs/xfs/xfs_file.c 2020-09-05 18:56:48.000000000 +0200 @@ -1223,14 +1223,21 @@ __xfs_filemap_fault( return ret; } +static inline bool +xfs_is_shared_dax_write_fault( + struct vm_fault *vmf) +{ + return IS_DAX(file_inode(vmf->vma->vm_file)) && + vmf->flags & FAULT_FLAG_WRITE && vmf->vma->vm_flags & VM_SHARED; +} + static vm_fault_t xfs_filemap_fault( struct vm_fault *vmf) { /* DAX can shortcut the normal fault path on write faults! */ return __xfs_filemap_fault(vmf, PE_SIZE_PTE, - IS_DAX(file_inode(vmf->vma->vm_file)) && - (vmf->flags & FAULT_FLAG_WRITE)); + xfs_is_shared_dax_write_fault(vmf)); } static vm_fault_t @@ -1243,7 +1250,7 @@ xfs_filemap_huge_fault( /* DAX can shortcut the normal fault path on write faults! */ return __xfs_filemap_fault(vmf, pe_size, - (vmf->flags & FAULT_FLAG_WRITE)); + xfs_is_shared_dax_write_fault(vmf)); } static vm_fault_t _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org