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mm: move memcmp_pages() and pages_identical()

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Patch series "THP aware uprobe", v13.

This patchset makes uprobe aware of THPs.

Currently, when uprobe is attached to text on THP, the page is split by
FOLL_SPLIT.  As a result, uprobe eliminates the performance benefit of
THP.

This set makes uprobe THP-aware.  Instead of FOLL_SPLIT, we introduces
FOLL_SPLIT_PMD, which only split PMD for uprobe.

After all uprobes within the THP are removed, the PTE-mapped pages are
regrouped as huge PMD.

This set (plus a few THP patches) is also available at

   https://github.com/liu-song-6/linux/tree/uprobe-thp

This patch (of 6):

Move memcmp_pages() to mm/util.c and pages_identical() to mm.h, so that we
can use them in other files.

Link: http://lkml.kernel.org/r/20190815164525.1848545-2-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <matthew.wilcox@oracle.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Song Liu 2019-09-23 15:38:19 -07:00 committed by Linus Torvalds
parent 87eaceb3fa
commit 010c164a5f
3 changed files with 20 additions and 18 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
include/linux/mm.h
View file

@ -2868,5 +2868,12 @@ void __init setup_nr_node_ids(void);
static inline void setup_nr_node_ids(void) {}
#endif
extern int memcmp_pages(struct page *page1, struct page *page2);
static inline int pages_identical(struct page *page1, struct page *page2)
{
return !memcmp_pages(page1, page2);
}
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */

18
mm/ksm.c
View file

@ -1029,24 +1029,6 @@ static u32 calc_checksum(struct page *page)
return checksum;
}
static int memcmp_pages(struct page *page1, struct page *page2)
{
char *addr1, *addr2;
int ret;
addr1 = kmap_atomic(page1);
addr2 = kmap_atomic(page2);
ret = memcmp(addr1, addr2, PAGE_SIZE);
kunmap_atomic(addr2);
kunmap_atomic(addr1);
return ret;
}
static inline int pages_identical(struct page *page1, struct page *page2)
{
return !memcmp_pages(page1, page2);
}
static int write_protect_page(struct vm_area_struct *vma, struct page *page,
pte_t *orig_pte)
{

13
mm/util.c
View file

@ -783,3 +783,16 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
out:
return res;
}
int memcmp_pages(struct page *page1, struct page *page2)
{
char *addr1, *addr2;
int ret;
addr1 = kmap_atomic(page1);
addr2 = kmap_atomic(page2);
ret = memcmp(addr1, addr2, PAGE_SIZE);
kunmap_atomic(addr2);
kunmap_atomic(addr1);
return ret;
}