Hello Peter, I made a number of tweaks to your recent patches to userfaultfd.2 and ioctl_userfaultfd.2. Many of the changes are cosmetic language fix-ups, but also I reworded a few things, notably "message" ==> "notification" for consistency (I think) with the rest of the page. Could you take a look at the patch below please, and let me know if there are any problems? Thanks, Michael diff --git a/man2/ioctl_userfaultfd.2 b/man2/ioctl_userfaultfd.2 index c29e0bb6a..365c1fa7b 100644 --- a/man2/ioctl_userfaultfd.2 +++ b/man2/ioctl_userfaultfd.2 @@ -212,7 +212,7 @@ memory accesses to the regions registered with userfaultfd. .BR UFFD_FEATURE_THREAD_ID " (since Linux 4.14)" If this feature bit is set, .I uffd_msg.pagefault.feat.ptid -will be set to the faulted thread ID for each page fault message. +will be set to the faulted thread ID for each page-fault message. .PP The returned .I ioctls @@ -450,7 +450,7 @@ Do not wake up the thread that waits for page-fault resolution Copy the page with read-only permission. This allows the user to trap the next write to the page, which will block and generate another write-protect userfault message. -This is only used when both +This is used only when both .B UFFDIO_REGISTER_MODE_MISSING and .B UFFDIO_REGISTER_MODE_WP @@ -667,7 +667,7 @@ structure was not a multiple of the system page size; or .I len was zero; or the specified range was otherwise invalid. .SS UFFDIO_WRITEPROTECT (Since Linux 5.7) -Write-protect or write-unprotect an userfaultfd registered memory range +Write-protect or write-unprotect a userfaultfd-registered memory range registered with mode .BR UFFDIO_REGISTER_MODE_WP . .PP @@ -693,13 +693,13 @@ When this mode bit is set, the ioctl will be a write-protect operation upon the memory range specified by .IR range . Otherwise it'll be a write-unprotect operation upon the specified range, -which can be used to resolve an userfaultfd write-protect page fault. +which can be used to resolve a userfaultfd write-protect page fault. .TP .B UFFDIO_WRITEPROTECT_MODE_DONTWAKE When this mode bit is set, do not wake up any thread that waits for page-fault resolution after the operation. -This could only be specified if +This can be specified only if .B UFFDIO_WRITEPROTECT_MODE_WP is not specified. .PP diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 index 0e9206424..3ff05af90 100644 --- a/man2/userfaultfd.2 +++ b/man2/userfaultfd.2 @@ -83,10 +83,10 @@ Userfaultfd supports two modes of registration: .BR UFFDIO_REGISTER_MODE_MISSING " (since 4.10)" When registered with .B UFFDIO_REGISTER_MODE_MISSING -mode, the userspace will receive a page fault message +mode, user-space will receive a page-fault notification when a missing page is accessed. The faulted thread will be stopped from execution until the page fault is -resolved from the userspace by either an +resolved from user-space by either an .B UFFDIO_COPY or an .B UFFDIO_ZEROPAGE @@ -95,17 +95,17 @@ ioctl. .BR UFFDIO_REGISTER_MODE_WP " (since 5.7)" When registered with .B UFFDIO_REGISTER_MODE_WP -mode, the userspace will receive a page fault message +mode, user-space will receive a page-fault notification when a write-protected page is written. The faulted thread will be stopped from execution -until the userspace write-unprotect the page using an +until user-space write-unprotects the page using an .B UFFDIO_WRITEPROTECT ioctl. .PP Multiple modes can be enabled at the same time for the same memory range. .PP -Since Linux 4.14, userfaultfd page fault message can selectively embed -faulting thread ID information into the fault message. +Since Linux 4.14, a userfaultfd page-fault notification can selectively embed +faulting thread ID information into the notification. One needs to enable this feature explicitly using the .B UFFD_FEATURE_THREAD_ID feature bit when initializing the userfaultfd context. @@ -177,10 +177,12 @@ One should check against the feature bit .B UFFD_FEATURE_PAGEFAULT_FLAG_WP before using this feature. Similar to the original userfaultfd missing mode, the write-protect mode will -generate an userfaultfd message when the protected page is written. +generate a userfaultfd notification when the protected page is written. The user needs to resolve the page fault by unprotecting the faulted page and -kick the faulted thread to continue. -For more information, please refer to "Userfaultfd write-protect mode" section. +kicking the faulted thread to continue. +For more information, +please refer to the "Userfaultfd write-protect mode" section. +.\" .SS Userfaultfd operation After the userfaultfd object is created with .BR userfaultfd (), @@ -276,11 +278,11 @@ with the mode set to .BR "UFFDIO_REGISTER_MODE_MISSING | UFFDIO_REGISTER_MODE_WP" . When there is only .B UFFDIO_REGISTER_MODE_WP -registered, the userspace will +registered, user-space will .I not -receive any message when a missing page is written. -Instead, the userspace will only receive a write-protect page fault message -when an existing but write-protected page got written. +receive any notification when a missing page is written. +Instead, user-space will receive a write-protect page-fault notification +only when an existing but write-protected page got written. .PP After the .B UFFDIO_REGISTER @@ -295,16 +297,17 @@ should be set to .BR UFFDIO_WRITEPROTECT_MODE_WP . .PP When a write-protect event happens, -the userspace will receive a page fault message whose +user-space will receive a page-fault notification whose .I uffd_msg.pagefault.flags will be with .B UFFD_PAGEFAULT_FLAG_WP flag set. -Note: since only writes can trigger such kind of fault, -write-protect messages will always be with +Note: since only writes can trigger this kind of fault, +write-protect notifications will always have the .B UFFD_PAGEFAULT_FLAG_WRITE -bit set too along with bit -.BR UFFD_PAGEFAULT_FLAG_WP . +bit set along with the +.BR UFFD_PAGEFAULT_FLAG_WP +bit. .PP To resolve a write-protection page fault, the user should initiate another .B UFFDIO_WRITEPROTECT @@ -314,7 +317,7 @@ should have the flag .B UFFDIO_WRITEPROTECT_MODE_WP cleared upon the faulted page or range. .PP -Write-protect mode only supports private anonymous memory. +Write-protect mode supports only private anonymous memory. .SS Reading from the userfaultfd structure Each .BR read (2) @@ -464,8 +467,8 @@ otherwise it is a read fault. .B UFFD_PAGEFAULT_FLAG_WP If the address is in a range that was registered with the .B UFFDIO_REGISTER_MODE_WP -flag, when this bit is set it means it's a write-protect fault. -Otherwise it's a page missing fault. +flag, when this bit is set, it means it's a write-protect fault. +Otherwise it's a page-missing fault. .RE .TP .I pagefault.feat.pid
