Hi [v3] * I'm re-posting the two DAX patches that fix the mmap-write after read problem with DAX. (No changes since [v2]) * I'm also posting a 3rd RFC patch to address what Jan said about fs_freeze and making mapping read-only. Jan Please review and see if this is what you meant. [v2] Jan Kara has pointed out that if we add the sb_start/end_pagefault pair in the new pfn_mkwrite we are then fixing another bug where: A user could start writing to the page while filesystem is frozen. [v1] The main problem is that current mm/memory.c will no call us with page_mkwrite if we do not have an actual page mapping, which is what DAX uses. The solution presented here introduces a new pfn_mkwrite to solve this problem. Please see patch-2 for details. I've been running with this patch for 4 month both HW and VMs with no apparent danger, but see patch-1 I played it safe. I am also posting an xfstest 080 that demonstrate this problem, I believe that also some git operations (can't remember which) suffer from this problem. Actually Eryu Guan found that this test fails on some other FS as well. List of patches: [PATCH 1/3] mm: New pfn_mkwrite same as page_mkwrite for VM_PFNMAP [PATCH 2/3] dax: use pfn_mkwrite to update c/mtime + freeze [PATCH 3/3] RFC: dax: dax_prepare_freeze [PATCH v4] xfstest: generic/080 test that mmap-write updates c/mtime Please I need that some mm person review the first patch? Andrew hi I believe this needs to eventually go through your tree. Please pick it up when you feel it is ready. I believe the first 2 are ready and fix real bugs. Matthew hi I would love to have your ACK on these patches? Thanks Boaz -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>