tree: https://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-next.git kill-mmap-sem-v5 head: c7a3e899803d98ae543468f0026500c651528a6c commit: c52634339df10df75f28787f431b937de3c3c591 [9/10] mm: introduce filemap_page_mkwrite_nommapsem reproduce: make htmldocs All warnings (new ones prefixed by >>): WARNING: convert(1) not found, for SVG to PDF conversion install ImageMagick (https://www.imagemagick.org) include/linux/srcu.h:175: warning: Function parameter or member 'p' not described in 'srcu_dereference_notrace' include/linux/srcu.h:175: warning: Function parameter or member 'sp' not described in 'srcu_dereference_notrace' include/linux/gfp.h:1: warning: no structured comments found >> mm/filemap.c:2882: warning: Function parameter or member 'mkwrite' not described in 'filemap_page_mkwrite_nommapsem' mm/filemap.c:2882: warning: Excess function parameter 'page_mkwrite_cb' description in 'filemap_page_mkwrite_nommapsem' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.ibss' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.connect' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.keys' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.ie' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.ie_len' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.bssid' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.ssid' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.default_key' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.default_mgmt_key' not described in 'wireless_dev' include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.prev_bssid_valid' not described in 'wireless_dev' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' description in 'reg_query_regdb_wmm' vim +2882 mm/filemap.c 2851 2852 /** 2853 * filemap_page_mkwrite_nommap_sem - handle dropping the mmap_sem and caching 2854 * the resulting page from the fs's mkwrite callback. 2855 * @vmf: struct vm_fault containing details of the fault 2856 * @page_mkwrite_cb: the fs specific mkwrite callback 2857 * 2858 * Some file systems have very heavy mkwrite operations, which means that we can 2859 * hold the mmap_sem for long periods of time. This can cause weird priority 2860 * inversions in the system if something tries to take a write lock on the 2861 * mmap_sem, which will block any new readers until the writer has done its 2862 * work. 2863 * 2864 * This helper allows file systems to opt-in to a mechanism that will handle 2865 * dropping the mmap_sem during the mkwrite, and then caching the result and 2866 * re-using the page in the next loop through the fault handler as long as it is 2867 * still valid. 2868 * 2869 * Users of this helper must be sure to _never_ access vmf->vma as it could be 2870 * invalid, instead they need to access vmf->file as that will either be pinned 2871 * because we grabbed a reference before dropping the mmap_sem, or we still have 2872 * the mmap_sem and thus is still save to look at. 2873 * 2874 * vma->vm_mm->mmap-sem must be held on entry. 2875 * 2876 * If our return value has VM_FAULT_RETRY set then the mmap_sem has been 2877 * dropped, otherwise it is still held. 2878 */ 2879 vm_fault_t filemap_page_mkwrite_nommapsem(struct vm_fault *vmf, 2880 page_mkwrite_cb *mkwrite) 2881 { > 2882 struct mm_struct *mm = vmf->vma->vm_mm; 2883 struct page *page = vmf->page; 2884 struct file *file = vmf->vma->vm_file; 2885 struct file *fpin; 2886 vm_fault_t ret; 2887 2888 /* 2889 * Our page is already initialized from a previous loop through the 2890 * fault handler, so lock it and check if it is valid, and if it is 2891 * simply return. 2892 */ 2893 if (vmf->flags & FAULT_FLAG_PAGE_INITIALISED) { 2894 lock_page(page); 2895 if (initialised_page_valid(vmf, page)) 2896 return VM_FAULT_LOCKED; 2897 unlock_page(page); 2898 } 2899 2900 /* 2901 * mkwrite can be expensive, so drop the mmap_sem for this operation and 2902 * deal with caching the page for the next trip around. 2903 */ 2904 fpin = maybe_unlock_mmap_for_io(vmf->vma, vmf->flags); 2905 vmf->file = file; 2906 ret = mkwrite(vmf); 2907 if (fpin) { 2908 if (ret == VM_FAULT_LOCKED) 2909 unlock_page(page); 2910 fput(fpin); 2911 2912 /* 2913 * We had an error when doing mkwrite, instead of looping 2914 * through again just down_read the mmap_sem and return the 2915 * error. Otherwise cache the page for the next trip through. 2916 */ 2917 if (ret & VM_FAULT_ERROR) { 2918 down_read(&mm->mmap_sem); 2919 } else { 2920 get_page(page); 2921 vmf->cached_page = page; 2922 ret = VM_FAULT_RETRY; 2923 } 2924 } 2925 return ret; 2926 } 2927 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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