* Re: kernel BUG at mm/hugetlb.c:LINE! [not found] ` <78313ae9-8596-9cbe-f648-3152660be9b3@oracle.com> @ 2020-05-22 10:05 ` Miklos Szeredi 2020-05-28 0:01 ` Mike Kravetz 0 siblings, 1 reply; 10+ messages in thread From: Miklos Szeredi @ 2020-05-22 10:05 UTC (permalink / raw) To: Mike Kravetz Cc: Colin Walters, syzbot, Andrew Morton, linux-fsdevel, linux-kernel, linux-mm, Miklos Szeredi, syzkaller-bugs, Al Viro, linux-unionfs On Wed, May 20, 2020 at 10:27:15AM -0700, Mike Kravetz wrote: > I am fairly confident it is all about checking limits and alignment. The > filesystem knows if it can/should align to base or huge page size. DAX has > some interesting additional restrictions, and several 'traditional' filesystems > check if they are 'on DAX'. Okay, I haven't looked at DAX vs. overlay. I'm sure it's going to come up at some point, if it hasn't already. > > In a previous e-mail, you suggested hugetlb_get_unmapped_area could do the > length adjustment in hugetlb_get_unmapped_area (generic and arch specific). > I agree, although there may be the need to add length overflow checks in > these routines (after round up) as this is done in core code now. However, > this can be done as a separate cleanup patch. > > In any case, we need to get the core mmap code to call filesystem specific > get_unmapped_area if on a union/overlay. The patch I suggested does this > by simply calling real_file to determine if there is a filesystem specific > get_unmapped_area. The other approach would be to provide an overlayfs > get_unmapped_area that calls the underlying filesystem get_unmapped_area. That latter is what's done for all other stacked operations in overlayfs. Untested patch below. Thanks, Miklos --- fs/overlayfs/file.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -757,6 +757,17 @@ static loff_t ovl_remap_file_range(struc remap_flags, op); } +static unsigned long ovl_get_unmapped_area(struct file *file, + unsigned long uaddr, unsigned long len, + unsigned long pgoff, unsigned long flags) +{ + struct file *realfile = file->private_data; + + return (realfile->f_op->get_unmapped_area ?: + current->mm->get_unmapped_area)(realfile, + uaddr, len, pgoff, flags); +} + const struct file_operations ovl_file_operations = { .open = ovl_open, .release = ovl_release, @@ -774,6 +785,7 @@ const struct file_operations ovl_file_op .copy_file_range = ovl_copy_file_range, .remap_file_range = ovl_remap_file_range, + .get_unmapped_area = ovl_get_unmapped_area, }; int __init ovl_aio_request_cache_init(void) ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: kernel BUG at mm/hugetlb.c:LINE! 2020-05-22 10:05 ` kernel BUG at mm/hugetlb.c:LINE! Miklos Szeredi @ 2020-05-28 0:01 ` Mike Kravetz 2020-05-28 8:37 ` [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() kbuild test robot 0 siblings, 1 reply; 10+ messages in thread From: Mike Kravetz @ 2020-05-28 0:01 UTC (permalink / raw) To: Miklos Szeredi Cc: Colin Walters, syzbot, Andrew Morton, linux-fsdevel, linux-kernel, linux-mm, Miklos Szeredi, syzkaller-bugs, Al Viro, linux-unionfs On 5/22/20 3:05 AM, Miklos Szeredi wrote: > On Wed, May 20, 2020 at 10:27:15AM -0700, Mike Kravetz wrote: > >> I am fairly confident it is all about checking limits and alignment. The >> filesystem knows if it can/should align to base or huge page size. DAX has >> some interesting additional restrictions, and several 'traditional' filesystems >> check if they are 'on DAX'. > > > Okay, I haven't looked at DAX vs. overlay. I'm sure it's going to come up at > some point, if it hasn't already. > >> >> In a previous e-mail, you suggested hugetlb_get_unmapped_area could do the >> length adjustment in hugetlb_get_unmapped_area (generic and arch specific). >> I agree, although there may be the need to add length overflow checks in >> these routines (after round up) as this is done in core code now. However, >> this can be done as a separate cleanup patch. >> >> In any case, we need to get the core mmap code to call filesystem specific >> get_unmapped_area if on a union/overlay. The patch I suggested does this >> by simply calling real_file to determine if there is a filesystem specific >> get_unmapped_area. The other approach would be to provide an overlayfs >> get_unmapped_area that calls the underlying filesystem get_unmapped_area. > > That latter is what's done for all other stacked operations in overlayfs. > > Untested patch below. > Thanks Miklos! We still need the 'real_file()' routine for is_file_hugepages. So combining these, I propose the following patch. It addresses the known issue as well as potential issues with is_file_hugepages returning incorrect information. I don't really like a separate header file for real_file, but I can not think of any good place to put it. Let me know what you think, From 33f6bbd19406108b61a4113b1ec8e4e6888cd482 Mon Sep 17 00:00:00 2001 From: Mike Kravetz <mike.kravetz@oracle.com> Date: Wed, 27 May 2020 16:58:58 -0700 Subject: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() If a file is on a union/overlay, then the 'struct file *' will have overlayfs file operations. The routine is_file_hugepages() compares f->f_op to hugetlbfs_file_operations to determine if it is a hugetlbfs file. If a hugetlbfs file is on a union/overlay, this comparison is false and is_file_hugepages() incorrectly indicates the underlying file is not hugetlbfs. One result of this is a BUG as shown in [1]. mmap uses is_file_hugepages() because hugetlbfs files have different alignment restrictions. In addition, mmap code would like to use the filesystem specific get_unmapped_area() routine if one is defined. To address this issue, - Add a new routine real_file() which will return the underlying file. - Update is_file_hugepages to get the real file. - Add get_unmapped_area f_op to oerrlayfs to call underlying routine. [1] https://lore.kernel.org/linux-mm/000000000000b4684e05a2968ca6@google.com/ Reported-by: syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> --- fs/overlayfs/file.c | 13 +++++++++++++ include/linux/hugetlb.h | 3 +++ include/linux/overlayfs.h | 27 +++++++++++++++++++++++++++ 3 files changed, 43 insertions(+) create mode 100644 include/linux/overlayfs.h diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 87c362f65448..cc020e1c72d5 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -12,6 +12,7 @@ #include <linux/splice.h> #include <linux/mm.h> #include <linux/fs.h> +#include <linux/overlayfs.h> #include "overlayfs.h" struct ovl_aio_req { @@ -757,6 +758,17 @@ static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in, remap_flags, op); } +static unsigned long ovl_get_unmapped_area(struct file *file, + unsigned long uaddr, unsigned long len, + unsigned long pgoff, unsigned long flags) +{ + struct file *realfile = real_file(file); + + return (realfile->f_op->get_unmapped_area ?: + current->mm->get_unmapped_area)(realfile, + uaddr, len, pgoff, flags); +} + const struct file_operations ovl_file_operations = { .open = ovl_open, .release = ovl_release, @@ -774,6 +786,7 @@ const struct file_operations ovl_file_operations = { .copy_file_range = ovl_copy_file_range, .remap_file_range = ovl_remap_file_range, + .get_unmapped_area = ovl_get_unmapped_area, }; int __init ovl_aio_request_cache_init(void) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 43a1cef8f0f1..fb22c0a7474a 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -9,6 +9,7 @@ #include <linux/cgroup.h> #include <linux/list.h> #include <linux/kref.h> +#include <linux/overlayfs.h> #include <asm/pgtable.h> struct ctl_table; @@ -437,6 +438,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size, vm_flags_t acct, static inline bool is_file_hugepages(struct file *file) { + file = real_file(file); + if (file->f_op == &hugetlbfs_file_operations) return true; diff --git a/include/linux/overlayfs.h b/include/linux/overlayfs.h new file mode 100644 index 000000000000..eecdfda0286f --- /dev/null +++ b/include/linux/overlayfs.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_OVERLAYFS_H +#define _LINUX_OVERLAYFS_H + +#include <linux/fs.h> + +extern const struct file_operations ovl_file_operations; + +#ifdef CONFIG_OVERLAY_FS +/* + * If file is on a union/overlay, then return the underlying real file. + * Otherwise return the file itself. + */ +static inline struct file *real_file(struct file *file) +{ + while (unlikely(file->f_op == &ovl_file_operations)) + file = file->private_data; + return file; +} +#else +static inline struct file *real_file(struct file *file) +{ + return file; +} +#endif + +#endif /* _LINUX_OVERLAYFS_H */ -- 2.25.4 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-05-28 0:01 ` Mike Kravetz @ 2020-05-28 8:37 ` kbuild test robot 2020-05-28 21:01 ` Mike Kravetz 0 siblings, 1 reply; 10+ messages in thread From: kbuild test robot @ 2020-05-28 8:37 UTC (permalink / raw) To: Mike Kravetz, Miklos Szeredi Cc: kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, Al Viro, linux-unionfs [-- Attachment #1: Type: text/plain, Size: 2140 bytes --] Hi Mike, I love your patch! Yet something to improve: [auto build test ERROR on miklos-vfs/overlayfs-next] [also build test ERROR on linus/master v5.7-rc7] [cannot apply to linux/master next-20200526] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Mike-Kravetz/ovl-provide-real_file-and-overlayfs-get_unmapped_area/20200528-080533 base: https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next config: h8300-randconfig-r036-20200528 (attached as .config) compiler: h8300-linux-gcc (GCC) 9.3.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=h8300 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp@intel.com> All error/warnings (new ones prefixed by >>, old ones prefixed by <<): fs/overlayfs/file.c: In function 'ovl_get_unmapped_area': >> fs/overlayfs/file.c:768:14: error: 'struct mm_struct' has no member named 'get_unmapped_area' 768 | current->mm->get_unmapped_area)(realfile, | ^~ >> fs/overlayfs/file.c:770:1: warning: control reaches end of non-void function [-Wreturn-type] 770 | } | ^ vim +768 fs/overlayfs/file.c 760 761 static unsigned long ovl_get_unmapped_area(struct file *file, 762 unsigned long uaddr, unsigned long len, 763 unsigned long pgoff, unsigned long flags) 764 { 765 struct file *realfile = real_file(file); 766 767 return (realfile->f_op->get_unmapped_area ?: > 768 current->mm->get_unmapped_area)(realfile, 769 uaddr, len, pgoff, flags); > 770 } 771 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org [-- Attachment #2: .config.gz --] [-- Type: application/gzip, Size: 31095 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-05-28 8:37 ` [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() kbuild test robot @ 2020-05-28 21:01 ` Mike Kravetz 2020-06-04 9:16 ` Miklos Szeredi 0 siblings, 1 reply; 10+ messages in thread From: Mike Kravetz @ 2020-05-28 21:01 UTC (permalink / raw) To: kbuild test robot, Miklos Szeredi Cc: kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, Al Viro, linux-unionfs On 5/28/20 1:37 AM, kbuild test robot wrote: > Hi Mike, > > I love your patch! Yet something to improve: > > [auto build test ERROR on miklos-vfs/overlayfs-next] > [also build test ERROR on linus/master v5.7-rc7] > [cannot apply to linux/master next-20200526] > [if your patch is applied to the wrong git tree, please drop us a note to help > improve the system. BTW, we also suggest to use '--base' option to specify the > base tree in git format-patch, please see https://stackoverflow.com/a/37406982] > > url: https://github.com/0day-ci/linux/commits/Mike-Kravetz/ovl-provide-real_file-and-overlayfs-get_unmapped_area/20200528-080533 > base: https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next > config: h8300-randconfig-r036-20200528 (attached as .config) > compiler: h8300-linux-gcc (GCC) 9.3.0 > reproduce (this is a W=1 build): > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > chmod +x ~/bin/make.cross > # save the attached .config to linux build tree > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=h8300 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kbuild test robot <lkp@intel.com> > > All error/warnings (new ones prefixed by >>, old ones prefixed by <<): > > fs/overlayfs/file.c: In function 'ovl_get_unmapped_area': >>> fs/overlayfs/file.c:768:14: error: 'struct mm_struct' has no member named 'get_unmapped_area' > 768 | current->mm->get_unmapped_area)(realfile, > | ^~ >>> fs/overlayfs/file.c:770:1: warning: control reaches end of non-void function [-Wreturn-type] > 770 | } > | ^ > > vim +768 fs/overlayfs/file.c > > 760 > 761 static unsigned long ovl_get_unmapped_area(struct file *file, > 762 unsigned long uaddr, unsigned long len, > 763 unsigned long pgoff, unsigned long flags) > 764 { > 765 struct file *realfile = real_file(file); > 766 > 767 return (realfile->f_op->get_unmapped_area ?: > > 768 current->mm->get_unmapped_area)(realfile, > 769 uaddr, len, pgoff, flags); > > 770 } > 771 > > --- > 0-DAY CI Kernel Test Service, Intel Corporation > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org > Well yuck! get_unmapped_area is not part of mm_struct if !CONFIG_MMU. Miklos, would adding '#ifdef CONFIG_MMU' around the overlayfs code be too ugly for you? Another option is to use real_file() in the mmap code as done in [1]. Sorry for all the questions. However, I want to make sure you are happy with any overlayfs changes. [1] https://lore.kernel.org/linux-mm/04a00e3b-539c-236f-e43b-0024ef94b7cb@oracle.com/ -- Mike Kravetz ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-05-28 21:01 ` Mike Kravetz @ 2020-06-04 9:16 ` Miklos Szeredi 2020-06-11 0:13 ` Mike Kravetz 0 siblings, 1 reply; 10+ messages in thread From: Miklos Szeredi @ 2020-06-04 9:16 UTC (permalink / raw) To: Mike Kravetz Cc: kbuild test robot, kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, Al Viro, overlayfs On Thu, May 28, 2020 at 11:01 PM Mike Kravetz <mike.kravetz@oracle.com> wrote: > > On 5/28/20 1:37 AM, kbuild test robot wrote: > > Hi Mike, > > > > I love your patch! Yet something to improve: > > > > [auto build test ERROR on miklos-vfs/overlayfs-next] > > [also build test ERROR on linus/master v5.7-rc7] > > [cannot apply to linux/master next-20200526] > > [if your patch is applied to the wrong git tree, please drop us a note to help > > improve the system. BTW, we also suggest to use '--base' option to specify the > > base tree in git format-patch, please see https://stackoverflow.com/a/37406982] > > > > url: https://github.com/0day-ci/linux/commits/Mike-Kravetz/ovl-provide-real_file-and-overlayfs-get_unmapped_area/20200528-080533 > > base: https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next > > config: h8300-randconfig-r036-20200528 (attached as .config) > > compiler: h8300-linux-gcc (GCC) 9.3.0 > > reproduce (this is a W=1 build): > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > chmod +x ~/bin/make.cross > > # save the attached .config to linux build tree > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=h8300 > > > > If you fix the issue, kindly add following tag as appropriate > > Reported-by: kbuild test robot <lkp@intel.com> > > > > All error/warnings (new ones prefixed by >>, old ones prefixed by <<): > > > > fs/overlayfs/file.c: In function 'ovl_get_unmapped_area': > >>> fs/overlayfs/file.c:768:14: error: 'struct mm_struct' has no member named 'get_unmapped_area' > > 768 | current->mm->get_unmapped_area)(realfile, > > | ^~ > >>> fs/overlayfs/file.c:770:1: warning: control reaches end of non-void function [-Wreturn-type] > > 770 | } > > | ^ > > > > vim +768 fs/overlayfs/file.c > > > > 760 > > 761 static unsigned long ovl_get_unmapped_area(struct file *file, > > 762 unsigned long uaddr, unsigned long len, > > 763 unsigned long pgoff, unsigned long flags) > > 764 { > > 765 struct file *realfile = real_file(file); > > 766 > > 767 return (realfile->f_op->get_unmapped_area ?: > > > 768 current->mm->get_unmapped_area)(realfile, > > 769 uaddr, len, pgoff, flags); > > > 770 } > > 771 > > > > --- > > 0-DAY CI Kernel Test Service, Intel Corporation > > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org > > > > Well yuck! get_unmapped_area is not part of mm_struct if !CONFIG_MMU. > > Miklos, would adding '#ifdef CONFIG_MMU' around the overlayfs code be too > ugly for you? Another option is to use real_file() in the mmap code as > done in [1]. I think the proper fix is to add an inline helper (call_get_unmapped_area()?) in linux/mm.h, and make that work properly for the NOMMU case as well. Thanks, Miklos ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-06-04 9:16 ` Miklos Szeredi @ 2020-06-11 0:13 ` Mike Kravetz 2020-06-11 0:37 ` Al Viro 0 siblings, 1 reply; 10+ messages in thread From: Mike Kravetz @ 2020-06-11 0:13 UTC (permalink / raw) To: Miklos Szeredi Cc: kbuild test robot, kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, Al Viro, overlayfs On 6/4/20 2:16 AM, Miklos Szeredi wrote: > On Thu, May 28, 2020 at 11:01 PM Mike Kravetz <mike.kravetz@oracle.com> wrote: >> >> Well yuck! get_unmapped_area is not part of mm_struct if !CONFIG_MMU. >> >> Miklos, would adding '#ifdef CONFIG_MMU' around the overlayfs code be too >> ugly for you? Another option is to use real_file() in the mmap code as >> done in [1]. > > I think the proper fix is to add an inline helper > (call_get_unmapped_area()?) in linux/mm.h, and make that work properly > for the NOMMU case as well. > I'm ignoring the above issue for now. There may be a more fundamental issue that I do not know how to solve without adding another memeber to file_operations. Why? In order to go from file -> realfile, one needs to do something like the code you provided. while (file->f_op == &ovl_file_operations) file = file->private_data; return file; The problem is that this needs to be called from core kernel code (is_file_hugepages in mmap). ovl_file_operations is obviously only defined in the overlayfs code. Since overlayfs can be built as a module, I do not know of a way to reference ovl_file_operations which will only become available when/if overlayfs is loaded. Is there a way to do that? If there is no other way to do this, then I think we need to add another member to file_operations as is done in the following patch. I hope there is another way, because adding another file_op seems like overkill. From 6d22c93284263b5ddcc2199adc1bcceb233f1499 Mon Sep 17 00:00:00 2001 From: Mike Kravetz <mike.kravetz@oracle.com> Date: Wed, 10 Jun 2020 16:23:46 -0700 Subject: [PATCH v3] ovl: add f_real file_operation and supporting code for overlayfs If a file is on a union/overlay, then the 'struct file *' will have overlayfs file operations. The routine is_file_hugepages() compares f->f_op to hugetlbfs_file_operations to determine if it is a hugetlbfs file. If a hugetlbfs file is on a union/overlay, this comparison is false and is_file_hugepages() incorrectly indicates the underlying file is not hugetlbfs. One result of this is a BUG as shown in [1]. mmap uses is_file_hugepages() to identify hugetlbfs file and potentially round up length because hugetlbfs files have different alignment restrictions. This is defined/expected behavior. In addition, mmap code would like to use the filesystem specific get_unmapped_area() routine if one is defined. To address this issue, - Add a new file operation f_real while will return the underlying file. Only overlayfs provides a function for this operation. - Add a new routine real_file() which can be used by core code get an underlying file. - Update is_file_hugepages to get the real file. - Add get_unmapped_area f_op to oerrlayfs to call underlying routine. [1] https://lore.kernel.org/linux-mm/000000000000b4684e05a2968ca6@google.com/ Reported-by: syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> --- fs/overlayfs/file.c | 23 +++++++++++++++++++++++ include/linux/fs.h | 8 ++++++++ include/linux/hugetlb.h | 2 ++ 3 files changed, 33 insertions(+) diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 87c362f65448..eb870fc3912f 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -757,6 +757,27 @@ static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in, remap_flags, op); } +#ifdef CONFIG_MMU +static unsigned long ovl_get_unmapped_area(struct file *file, + unsigned long uaddr, unsigned long len, + unsigned long pgoff, unsigned long flags) +{ + file = real_file(file); + + return (file->f_op->get_unmapped_area ?: + current->mm->get_unmapped_area)(file, uaddr, len, pgoff, flags); +} +#else +#define ovl_get_unmapped_area NULL +#endif + +static struct file *ovl_f_real(struct file *file) +{ + while (file->f_op == &ovl_file_operations) + file = file->private_data; + return file; +} + const struct file_operations ovl_file_operations = { .open = ovl_open, .release = ovl_release, @@ -771,9 +792,11 @@ const struct file_operations ovl_file_operations = { .compat_ioctl = ovl_compat_ioctl, .splice_read = ovl_splice_read, .splice_write = ovl_splice_write, + .f_real = ovl_f_real, .copy_file_range = ovl_copy_file_range, .remap_file_range = ovl_remap_file_range, + .get_unmapped_area = ovl_get_unmapped_area, }; int __init ovl_aio_request_cache_init(void) diff --git a/include/linux/fs.h b/include/linux/fs.h index 45cc10cdf6dd..59a969549aec 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1863,6 +1863,7 @@ struct file_operations { struct file *file_out, loff_t pos_out, loff_t len, unsigned int remap_flags); int (*fadvise)(struct file *, loff_t, loff_t, int); + struct file * (*f_real)(struct file *file); } __randomize_layout; struct inode_operations { @@ -1895,6 +1896,13 @@ struct inode_operations { int (*set_acl)(struct inode *, struct posix_acl *, int); } ____cacheline_aligned; +static inline struct file *real_file(struct file *file) +{ + if (unlikely(file->f_op->f_real)) + return file->f_op->f_real(file); + return file; +} + static inline ssize_t call_read_iter(struct file *file, struct kiocb *kio, struct iov_iter *iter) { diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 43a1cef8f0f1..528b07145414 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -437,6 +437,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size, vm_flags_t acct, static inline bool is_file_hugepages(struct file *file) { + file = real_file(file); + if (file->f_op == &hugetlbfs_file_operations) return true; -- 2.25.4 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-06-11 0:13 ` Mike Kravetz @ 2020-06-11 0:37 ` Al Viro 2020-06-11 1:36 ` Matthew Wilcox 0 siblings, 1 reply; 10+ messages in thread From: Al Viro @ 2020-06-11 0:37 UTC (permalink / raw) To: Mike Kravetz Cc: Miklos Szeredi, kbuild test robot, kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, overlayfs On Wed, Jun 10, 2020 at 05:13:52PM -0700, Mike Kravetz wrote: > To address this issue, > - Add a new file operation f_real while will return the underlying file. > Only overlayfs provides a function for this operation. > - Add a new routine real_file() which can be used by core code get an > underlying file. > - Update is_file_hugepages to get the real file. Egads... So to find out whether it's a hugetlb you would * check if a method is NULL * if not, call it * ... and check if the method table of the result is hugetlbfs one? Here's a radical suggestion: FMODE_HUGEPAGES. Just have it set by ->open() and let is_file_hugepages() check it. In ->f_mode. And make the bloody hugetlbfs_file_operations static, while we are at it. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-06-11 0:37 ` Al Viro @ 2020-06-11 1:36 ` Matthew Wilcox 2020-06-11 2:17 ` Al Viro 0 siblings, 1 reply; 10+ messages in thread From: Matthew Wilcox @ 2020-06-11 1:36 UTC (permalink / raw) To: Al Viro Cc: Mike Kravetz, Miklos Szeredi, kbuild test robot, kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, overlayfs On Thu, Jun 11, 2020 at 01:37:26AM +0100, Al Viro wrote: > On Wed, Jun 10, 2020 at 05:13:52PM -0700, Mike Kravetz wrote: > > > To address this issue, > > - Add a new file operation f_real while will return the underlying file. > > Only overlayfs provides a function for this operation. > > - Add a new routine real_file() which can be used by core code get an > > underlying file. > > - Update is_file_hugepages to get the real file. > > Egads... So to find out whether it's a hugetlb you would > * check if a method is NULL > * if not, call it > * ... and check if the method table of the result is hugetlbfs one? > > Here's a radical suggestion: FMODE_HUGEPAGES. Just have it set by > ->open() and let is_file_hugepages() check it. In ->f_mode. And > make the bloody hugetlbfs_file_operations static, while we are at it. ITYM FMODE_OVL_UPPER. To quote Mike: > while (file->f_op == &ovl_file_operations) > file = file->private_data; > return file; which would be transformed into: while (file->f_mode & FMODE_OVL_UPPER) file = file->private_data; return file; Or are you proposing that overlayfs copy FMODE_HUGEPAGES from the underlying fs to the overlaying fs? ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-06-11 1:36 ` Matthew Wilcox @ 2020-06-11 2:17 ` Al Viro 2020-06-11 2:31 ` Mike Kravetz 0 siblings, 1 reply; 10+ messages in thread From: Al Viro @ 2020-06-11 2:17 UTC (permalink / raw) To: Matthew Wilcox Cc: Mike Kravetz, Miklos Szeredi, kbuild test robot, kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, overlayfs On Wed, Jun 10, 2020 at 06:36:16PM -0700, Matthew Wilcox wrote: > while (file->f_mode & FMODE_OVL_UPPER) > file = file->private_data; > return file; > > Or are you proposing that overlayfs copy FMODE_HUGEPAGES from the > underlying fs to the overlaying fs? The latter - that way nobody outside of overlayfs needs to know what its ->private_data points to, for one thing. And it's cheaper that way, obviously. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() 2020-06-11 2:17 ` Al Viro @ 2020-06-11 2:31 ` Mike Kravetz 0 siblings, 0 replies; 10+ messages in thread From: Mike Kravetz @ 2020-06-11 2:31 UTC (permalink / raw) To: Al Viro, Matthew Wilcox Cc: Miklos Szeredi, kbuild test robot, kbuild-all, Colin Walters, syzbot, Andrew Morton, Linux Memory Management List, linux-fsdevel, linux-kernel, syzkaller-bugs, overlayfs On 6/10/20 7:17 PM, Al Viro wrote: > On Wed, Jun 10, 2020 at 06:36:16PM -0700, Matthew Wilcox wrote: > >> while (file->f_mode & FMODE_OVL_UPPER) >> file = file->private_data; >> return file; >> >> Or are you proposing that overlayfs copy FMODE_HUGEPAGES from the >> underlying fs to the overlaying fs? > > The latter - that way nobody outside of overlayfs needs to know what > its ->private_data points to, for one thing. And it's cheaper that > way, obviously. > Thanks Al and Matthew! I knew adding a file op for this was overkill and was looking for other suggestions. -- Mike Kravetz ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2020-06-11 2:32 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <000000000000b4684e05a2968ca6@google.com> [not found] ` <aa7812b8-60ae-8578-40db-e71ad766b4d3@oracle.com> [not found] ` <CAJfpegtVca6H1JPW00OF-7sCwpomMCo=A2qr5K=9uGKEGjEp3w@mail.gmail.com> [not found] ` <bb232cfa-5965-42d0-88cf-46d13f7ebda3@www.fastmail.com> [not found] ` <9a56a79a-88ed-9ff4-115e-ec169cba5c0b@oracle.com> [not found] ` <CAJfpegsNVB12MQ-Jgbb-f=+i3g0Xy52miT3TmUAYL951HVQS_w@mail.gmail.com> [not found] ` <78313ae9-8596-9cbe-f648-3152660be9b3@oracle.com> 2020-05-22 10:05 ` kernel BUG at mm/hugetlb.c:LINE! Miklos Szeredi 2020-05-28 0:01 ` Mike Kravetz 2020-05-28 8:37 ` [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area() kbuild test robot 2020-05-28 21:01 ` Mike Kravetz 2020-06-04 9:16 ` Miklos Szeredi 2020-06-11 0:13 ` Mike Kravetz 2020-06-11 0:37 ` Al Viro 2020-06-11 1:36 ` Matthew Wilcox 2020-06-11 2:17 ` Al Viro 2020-06-11 2:31 ` Mike Kravetz
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