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alistair23-linux/include/linux/khugepaged.h

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 08:07:57 -06:00
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_KHUGEPAGED_H
#define _LINUX_KHUGEPAGED_H
#include <linux/sched/coredump.h> /* MMF_VM_HUGEPAGE */
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
extern struct attribute_group khugepaged_attr_group;
extern int khugepaged_init(void);
extern void khugepaged_destroy(void);
extern int start_stop_khugepaged(void);
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extern int __khugepaged_enter(struct mm_struct *mm);
extern void __khugepaged_exit(struct mm_struct *mm);
extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
unsigned long vm_flags);
extern void khugepaged_min_free_kbytes_update(void);
khugepaged: enable collapse pmd for pte-mapped THP khugepaged needs exclusive mmap_sem to access page table. When it fails to lock mmap_sem, the page will fault in as pte-mapped THP. As the page is already a THP, khugepaged will not handle this pmd again. This patch enables the khugepaged to retry collapse the page table. struct mm_slot (in khugepaged.c) is extended with an array, containing addresses of pte-mapped THPs. We use array here for simplicity. We can easily replace it with more advanced data structures when needed. In khugepaged_scan_mm_slot(), if the mm contains pte-mapped THP, we try to collapse the page table. Since collapse may happen at an later time, some pages may already fault in. collapse_pte_mapped_thp() is added to properly handle these pages. collapse_pte_mapped_thp() also double checks whether all ptes in this pmd are mapping to the same THP. This is necessary because some subpage of the THP may be replaced, for example by uprobe. In such cases, it is not possible to collapse the pmd. [kirill.shutemov@linux.intel.com: add comments for retract_page_tables()] Link: http://lkml.kernel.org/r/20190816145443.6ard3iilytc6jlgv@box Link: http://lkml.kernel.org/r/20190815164525.1848545-6-songliubraving@fb.com Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#ifdef CONFIG_SHMEM
extern void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr);
#else
static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
unsigned long addr)
{
}
#endif
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#define khugepaged_enabled() \
(transparent_hugepage_flags & \
((1<<TRANSPARENT_HUGEPAGE_FLAG) | \
(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)))
#define khugepaged_always() \
(transparent_hugepage_flags & \
(1<<TRANSPARENT_HUGEPAGE_FLAG))
#define khugepaged_req_madv() \
(transparent_hugepage_flags & \
(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG))
#define khugepaged_defrag() \
(transparent_hugepage_flags & \
(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG))
static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
if (test_bit(MMF_VM_HUGEPAGE, &oldmm->flags))
return __khugepaged_enter(mm);
return 0;
}
static inline void khugepaged_exit(struct mm_struct *mm)
{
if (test_bit(MMF_VM_HUGEPAGE, &mm->flags))
__khugepaged_exit(mm);
}
static inline int khugepaged_enter(struct vm_area_struct *vma,
unsigned long vm_flags)
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{
if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags))
if ((khugepaged_always() ||
(khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) &&
mm: make PR_SET_THP_DISABLE immediately active PR_SET_THP_DISABLE has a rather subtle semantic. It doesn't affect any existing mapping because it only updated mm->def_flags which is a template for new mappings. The mappings created after prctl(PR_SET_THP_DISABLE) have VM_NOHUGEPAGE flag set. This can be quite surprising for all those applications which do not do prctl(); fork() & exec() and want to control their own THP behavior. Another usecase when the immediate semantic of the prctl might be useful is a combination of pre- and post-copy migration of containers with CRIU. In this case CRIU populates a part of a memory region with data that was saved during the pre-copy stage. Afterwards, the region is registered with userfaultfd and CRIU expects to get page faults for the parts of the region that were not yet populated. However, khugepaged collapses the pages and the expected page faults do not occur. In more general case, the prctl(PR_SET_THP_DISABLE) could be used as a temporary mechanism for enabling/disabling THP process wide. Implementation wise, a new MMF_DISABLE_THP flag is added. This flag is tested when decision whether to use huge pages is taken either during page fault of at the time of THP collapse. It should be noted, that the new implementation makes PR_SET_THP_DISABLE master override to any per-VMA setting, which was not the case previously. Fixes: a0715cc22601 ("mm, thp: add VM_INIT_DEF_MASK and PRCTL_THP_DISABLE") Link: http://lkml.kernel.org/r/1496415802-30944-1-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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!(vm_flags & VM_NOHUGEPAGE) &&
!test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
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if (__khugepaged_enter(vma->vm_mm))
return -ENOMEM;
return 0;
}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
return 0;
}
static inline void khugepaged_exit(struct mm_struct *mm)
{
}
static inline int khugepaged_enter(struct vm_area_struct *vma,
unsigned long vm_flags)
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{
return 0;
}
static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
unsigned long vm_flags)
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{
return 0;
}
khugepaged: enable collapse pmd for pte-mapped THP khugepaged needs exclusive mmap_sem to access page table. When it fails to lock mmap_sem, the page will fault in as pte-mapped THP. As the page is already a THP, khugepaged will not handle this pmd again. This patch enables the khugepaged to retry collapse the page table. struct mm_slot (in khugepaged.c) is extended with an array, containing addresses of pte-mapped THPs. We use array here for simplicity. We can easily replace it with more advanced data structures when needed. In khugepaged_scan_mm_slot(), if the mm contains pte-mapped THP, we try to collapse the page table. Since collapse may happen at an later time, some pages may already fault in. collapse_pte_mapped_thp() is added to properly handle these pages. collapse_pte_mapped_thp() also double checks whether all ptes in this pmd are mapping to the same THP. This is necessary because some subpage of the THP may be replaced, for example by uprobe. In such cases, it is not possible to collapse the pmd. [kirill.shutemov@linux.intel.com: add comments for retract_page_tables()] Link: http://lkml.kernel.org/r/20190816145443.6ard3iilytc6jlgv@box Link: http://lkml.kernel.org/r/20190815164525.1848545-6-songliubraving@fb.com Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
unsigned long addr)
{
}
static inline void khugepaged_min_free_kbytes_update(void)
{
}
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif /* _LINUX_KHUGEPAGED_H */