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authorPavel Emelyanov <xemul@parallels.com>2012-01-10 15:11:23 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-10 16:30:54 -0800
commit640708a2cff7f81e246243b0073c66e6ece7e53e (patch)
tree8cc00ae2b374bf6750ad9ca20da3566e28cfc9ff /include
parent7773fbc54182a90cd248656619c7d33859e5f91d (diff)
procfs: introduce the /proc/<pid>/map_files/ directory
This one behaves similarly to the /proc/<pid>/fd/ one - it contains symlinks one for each mapping with file, the name of a symlink is "vma->vm_start-vma->vm_end", the target is the file. Opening a symlink results in a file that point exactly to the same inode as them vma's one. For example the ls -l of some arbitrary /proc/<pid>/map_files/ | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80403000-7f8f80404000 -> /lib64/libc-2.5.so | lr-x------ 1 root root 64 Aug 26 06:40 7f8f8061e000-7f8f80620000 -> /lib64/libselinux.so.1 | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80826000-7f8f80827000 -> /lib64/libacl.so.1.1.0 | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80a2f000-7f8f80a30000 -> /lib64/librt-2.5.so | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80a30000-7f8f80a4c000 -> /lib64/ld-2.5.so This *helps* checkpointing process in three ways: 1. When dumping a task mappings we do know exact file that is mapped by particular region. We do this by opening /proc/$pid/map_files/$address symlink the way we do with file descriptors. 2. This also helps in determining which anonymous shared mappings are shared with each other by comparing the inodes of them. 3. When restoring a set of processes in case two of them has a mapping shared, we map the memory by the 1st one and then open its /proc/$pid/map_files/$address file and map it by the 2nd task. Using /proc/$pid/maps for this is quite inconvenient since it brings repeatable re-reading and reparsing for this text file which slows down restore procedure significantly. Also as being pointed in (3) it is a way easier to use top level shared mapping in children as /proc/$pid/map_files/$address when needed. [akpm@linux-foundation.org: coding-style fixes] [gorcunov@openvz.org: make map_files depend on CHECKPOINT_RESTORE] Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Reviewed-by: Vasiliy Kulikov <segoon@openwall.com> Reviewed-by: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Tejun Heo <tj@kernel.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5568553a41f..6eba2cc016c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1482,6 +1482,18 @@ static inline unsigned long vma_pages(struct vm_area_struct *vma)
return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
}
+/* Look up the first VMA which exactly match the interval vm_start ... vm_end */
+static inline struct vm_area_struct *find_exact_vma(struct mm_struct *mm,
+ unsigned long vm_start, unsigned long vm_end)
+{
+ struct vm_area_struct *vma = find_vma(mm, vm_start);
+
+ if (vma && (vma->vm_start != vm_start || vma->vm_end != vm_end))
+ vma = NULL;
+
+ return vma;
+}
+
#ifdef CONFIG_MMU
pgprot_t vm_get_page_prot(unsigned long vm_flags);
#else