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authorOleg Nesterov <oleg@redhat.com>2014-05-05 16:38:18 +0200
committerOleg Nesterov <oleg@redhat.com>2014-05-14 13:57:24 +0200
commit29dedee0e693aa113164c820395ce51446a71ace (patch)
tree7dff2a1f28a6c2d300c14fbe3674f3756f4dea7a /kernel
parent8e02ae573e6ae86930d08662790827a938203e70 (diff)
downloadlinux-29dedee0e693aa113164c820395ce51446a71ace.tar.gz
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uprobes: Add mem_cgroup_charge_anon() into uprobe_write_opcode()
Hugh says: The one I noticed was that it forgets all about memcg (because it was copied from KSM, and there the replacement page has already been charged to a memcg). See how mm/memory.c do_anonymous_page() does a mem_cgroup_charge_anon(). Hopefully not a big problem, uprobes is a system-wide thing and only root can insert the probes. But I agree, should be fixed anyway. Add mem_cgroup_{un,}charge_anon() into uprobe_write_opcode(). To simplify the error handling (and avoid the new "uncharge" label) the patch also moves anon_vma_prepare() up before we alloc/charge the new page. While at it fix the comment about ->mmap_sem, it is held for write. Suggested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/uprobes.c23
1 files changed, 11 insertions, 12 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 7716c40f2c50..a13251e8bfa4 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -279,18 +279,13 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t
* supported by that architecture then we need to modify is_trap_at_addr and
* uprobe_write_opcode accordingly. This would never be a problem for archs
* that have fixed length instructions.
- */
-
-/*
+ *
* uprobe_write_opcode - write the opcode at a given virtual address.
* @mm: the probed process address space.
* @vaddr: the virtual address to store the opcode.
* @opcode: opcode to be written at @vaddr.
*
- * Called with mm->mmap_sem held (for read and with a reference to
- * mm).
- *
- * For mm @mm, write the opcode at @vaddr.
+ * Called with mm->mmap_sem held for write.
* Return 0 (success) or a negative errno.
*/
int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
@@ -310,21 +305,25 @@ retry:
if (ret <= 0)
goto put_old;
+ ret = anon_vma_prepare(vma);
+ if (ret)
+ goto put_old;
+
ret = -ENOMEM;
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
if (!new_page)
goto put_old;
- __SetPageUptodate(new_page);
+ if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))
+ goto put_new;
+ __SetPageUptodate(new_page);
copy_highpage(new_page, old_page);
copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
- ret = anon_vma_prepare(vma);
- if (ret)
- goto put_new;
-
ret = __replace_page(vma, vaddr, old_page, new_page);
+ if (ret)
+ mem_cgroup_uncharge_page(new_page);
put_new:
page_cache_release(new_page);