The patch titled
mm: move migrate_prep out from under mmap_sem
has been added to the -mm tree. Its filename is
mm-move-migrate_prep-out-from-under-mmap_sem.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mm: move migrate_prep out from under mmap_sem
From: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Move the migrate_prep outside the mmap_sem for the following system calls
1. sys_move_pages
2. sys_migrate_pages
3. sys_mbind()
It really does not matter when we flush the lru. The system is free to
add pages onto the lru even during migration which will make the page
migration either skip the page (mbind, migrate_pages) or return a busy
state (move_pages).
Fixes this lockdep warning (and potential deadlock):
Some VM place has
mmap_sem -> kevent_wq via lru_add_drain_all()
net/core/dev.c::dev_ioctl() has
rtnl_lock -> mmap_sem (*) the ioctl has copy_from_user() and it can do page fault.
linkwatch_event has
kevent_wq -> rtnl_lock
Signed-off-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Reported-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 18 +++++++++++-------
mm/migrate.c | 2 +-
2 files changed, 12 insertions(+), 8 deletions(-)
diff -puN mm/mempolicy.c~mm-move-migrate_prep-out-from-under-mmap_sem mm/mempolicy.c
--- a/mm/mempolicy.c~mm-move-migrate_prep-out-from-under-mmap_sem
+++ a/mm/mempolicy.c
@@ -489,12 +489,6 @@ check_range(struct mm_struct *mm, unsign
int err;
struct vm_area_struct *first, *vma, *prev;
- if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
-
- err = migrate_prep();
- if (err)
- return ERR_PTR(err);
- }
first = find_vma(mm, start);
if (!first)
@@ -809,9 +803,13 @@ int do_migrate_pages(struct mm_struct *m
const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags)
{
int busy = 0;
- int err = 0;
+ int err;
nodemask_t tmp;
+ err = migrate_prep();
+ if (err)
+ return err;
+
down_read(&mm->mmap_sem);
err = migrate_vmas(mm, from_nodes, to_nodes, flags);
@@ -974,6 +972,12 @@ static long do_mbind(unsigned long start
start, start + len, mode, mode_flags,
nmask ? nodes_addr(*nmask)[0] : -1);
+ if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+
+ err = migrate_prep();
+ if (err)
+ return err;
+ }
down_write(&mm->mmap_sem);
vma = check_range(mm, start, end, nmask,
flags | MPOL_MF_INVERT, &pagelist);
diff -puN mm/migrate.c~mm-move-migrate_prep-out-from-under-mmap_sem mm/migrate.c
--- a/mm/migrate.c~mm-move-migrate_prep-out-from-under-mmap_sem
+++ a/mm/migrate.c
@@ -841,12 +841,12 @@ static int do_move_page_to_node_array(st
struct page_to_node *pp;
LIST_HEAD(pagelist);
+ migrate_prep();
down_read(&mm->mmap_sem);
/*
* Build a list of pages to migrate
*/
- migrate_prep();
for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
struct vm_area_struct *vma;
struct page *page;
_
Patches currently in -mm which might be from cl@xxxxxxxxxxxxxxxxxxxx are
repeatable-slab-corruption-with-ltp-msgctl08.patch
linux-next.patch
hugetlbfs-handle-pages-higher-order-than-max_order.patch
hugetlb-pull-gigantic-page-initialisation-out-of-the-default-path.patch
oom-do-not-dump-task-state-for-non-thread-group-leaders.patch
mm-move-migrate_prep-out-from-under-mmap_sem.patch
mm-rework-do_pages_move-to-work-on-page_sized-chunks.patch
mm-rework-do_pages_move-to-work-on-page_sized-chunks-update.patch
mm-move_pages-no-need-to-set-pp-page-to-zero_page0-by-default.patch
reiser4.patch
slab-leaks3-default-y.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
