From 28bd65781c848d95ba6a7f58b5c4b8265a804ec6 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 25 Jan 2011 15:07:26 -0800 Subject: mm: migration: clarify migrate_pages() comment Callers of migrate_pages should putback_lru_pages to return pages isolated to LRU or free list. Now comment is rather confusing. It says caller always have to call it. It is more clear to point out that the caller has to call it if migrate_pages's return value isn't zero. Signed-off-by: Minchan Kim Cc: Christoph Lameter Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/migrate.c') diff --git a/mm/migrate.c b/mm/migrate.c index 46fe8cc13d67..9f29a3b7aac2 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -888,7 +888,7 @@ out: * are movable anymore because to has become empty * or no retryable pages exist anymore. * Caller should call putback_lru_pages to return pages to the LRU - * or free list. + * or free list only if ret != 0. * * Return: Number of pages not migrated or error code. */ -- cgit v1.2.3 From 57fc4a5ee322cde96c33f101d3c2d3b79011c05c Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Tue, 1 Feb 2011 15:52:32 -0800 Subject: mm: when migrate_pages returns 0, all pages must have been released In some cases migrate_pages could return zero while still leaving a few pages in the pagelist (and some caller wouldn't notice it has to call putback_lru_pages after commit cf608ac19c9 ("mm: compaction: fix COMPACTPAGEFAILED counting")). Add one missing putback_lru_pages not added by commit cf608ac19c95 ("mm: compaction: fix COMPACTPAGEFAILED counting"). Signed-off-by: Andrea Arcangeli Signed-off-by: Minchan Kim Reviewed-by: Minchan Kim Cc: Christoph Lameter Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory-failure.c | 1 + mm/migrate.c | 3 +-- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/migrate.c') diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 548fbd70f026..75398b0bfede 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1419,6 +1419,7 @@ int soft_offline_page(struct page *page, int flags) ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0, true); if (ret) { + putback_lru_pages(&pagelist); pr_info("soft offline: %#lx: migration failed %d, type %lx\n", pfn, ret, page->flags); if (ret > 0) diff --git a/mm/migrate.c b/mm/migrate.c index 9f29a3b7aac2..155a2e9a8059 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -772,6 +772,7 @@ uncharge: unlock: unlock_page(page); +move_newpage: if (rc != -EAGAIN) { /* * A page that has been migrated has all references @@ -785,8 +786,6 @@ unlock: putback_lru_page(page); } -move_newpage: - /* * Move the new page to the LRU. If migration was not successful * then this will free the page. -- cgit v1.2.3 From 48db54ee2f41e8ae2faf330b55db34a9fffb5b3c Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 1 Feb 2011 15:52:33 -0800 Subject: mm/migration: fix page corruption during hugepage migration If migrate_huge_page by memory-failure fails , it calls put_page in itself to decrease page reference and caller of migrate_huge_page also calls putback_lru_pages. It can do double free of page so it can make page corruption on page holder. In addtion, clean of pages on caller is consistent behavior with migrate_pages by cf608ac19c ("mm: compaction: fix COMPACTPAGEFAILED counting"). Signed-off-by: Minchan Kim Cc: Andrea Arcangeli Cc: Christoph Lameter Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory-failure.c | 5 ++++- mm/migrate.c | 4 ---- 2 files changed, 4 insertions(+), 5 deletions(-) (limited to 'mm/migrate.c') diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 75398b0bfede..237aaa488f4e 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1295,7 +1295,10 @@ static int soft_offline_huge_page(struct page *page, int flags) ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0, true); if (ret) { - putback_lru_pages(&pagelist); + struct page *page1, *page2; + list_for_each_entry_safe(page1, page2, &pagelist, lru) + put_page(page1); + pr_debug("soft offline: %#lx: migration failed %d, type %lx\n", pfn, ret, page->flags); if (ret > 0) diff --git a/mm/migrate.c b/mm/migrate.c index 155a2e9a8059..766115253807 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -980,10 +980,6 @@ int migrate_huge_pages(struct list_head *from, } rc = 0; out: - - list_for_each_entry_safe(page, page2, from, lru) - put_page(page); - if (rc) return rc; -- cgit v1.2.3 From a879bf582dfb3a79d30d76ca3af2ae8a0f39010c Mon Sep 17 00:00:00 2001 From: Greg Thelen Date: Fri, 25 Feb 2011 14:44:13 -0800 Subject: mm: grab rcu read lock in move_pages() The move_pages() usage of find_task_by_vpid() requires rcu_read_lock() to prevent free_pid() from reclaiming the pid. Without this patch, RCU warnings are printed in v2.6.38-rc4 move_pages() with: CONFIG_LOCKUP_DETECTOR=y CONFIG_PREEMPT=y CONFIG_LOCKDEP=y CONFIG_PROVE_LOCKING=y CONFIG_PROVE_RCU=y Previously, migrate_pages() went through a similar transformation replacing usage of tasklist_lock with rcu read lock: commit 55cfaa3cbdd29c4919ecb5fb8965c310f357e48c Author: Zeng Zhaoming Date: Thu Dec 2 14:31:13 2010 -0800 mm/mempolicy.c: add rcu read lock to protect pid structure commit 1e50df39f6e2c3a4a3394df62baa8a213df16c54 Author: KOSAKI Motohiro Date: Thu Jan 13 15:46:14 2011 -0800 mempolicy: remove tasklist_lock from migrate_pages Signed-off-by: Greg Thelen Cc: Mel Gorman Cc: Minchan Kim Cc: Rik van Riel Cc: KAMEZAWA Hiroyuki Cc: "Paul E. McKenney" Cc: Tetsuo Handa Cc: Sergey Senozhatsky Cc: Oleg Nesterov Cc: Zeng Zhaoming Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/migrate.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/migrate.c') diff --git a/mm/migrate.c b/mm/migrate.c index 766115253807..352de555626c 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1287,14 +1287,14 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, return -EPERM; /* Find the mm_struct */ - read_lock(&tasklist_lock); + rcu_read_lock(); task = pid ? find_task_by_vpid(pid) : current; if (!task) { - read_unlock(&tasklist_lock); + rcu_read_unlock(); return -ESRCH; } mm = get_task_mm(task); - read_unlock(&tasklist_lock); + rcu_read_unlock(); if (!mm) return -EINVAL; -- cgit v1.2.3