From dcf6a79dda5cc2a2bec183e50d829030c0972aaa Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Mon, 2 Feb 2009 18:33:49 +0200 Subject: write-back: fix nr_to_write counter Commit 05fe478dd04e02fa230c305ab9b5616669821dd3 introduced some @wbc->nr_to_write breakage. It made the following changes: 1. Decrement wbc->nr_to_write instead of nr_to_write 2. Decrement wbc->nr_to_write _only_ if wbc->sync_mode == WB_SYNC_NONE 3. If synced nr_to_write pages, stop only if if wbc->sync_mode == WB_SYNC_NONE, otherwise keep going. However, according to the commit message, the intention was to only make change 3. Change 1 is a bug. Change 2 does not seem to be necessary, and it breaks UBIFS expectations, so if needed, it should be done separately later. And change 2 does not seem to be documented in the commit message. This patch does the following: 1. Undo changes 1 and 2 2. Add a comment explaining change 3 (it very useful to have comments in _code_, not only in the commit). Signed-off-by: Artem Bityutskiy Acked-by: Nick Piggin Cc: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page-writeback.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index b493db7841dc..dc32dae01e5f 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1051,13 +1051,22 @@ continue_unlock: } } - if (wbc->sync_mode == WB_SYNC_NONE) { - wbc->nr_to_write--; - if (wbc->nr_to_write <= 0) { - done = 1; - break; - } + if (nr_to_write > 0) + nr_to_write--; + else if (wbc->sync_mode == WB_SYNC_NONE) { + /* + * We stop writing back only if we are not + * doing integrity sync. In case of integrity + * sync we have to keep going because someone + * may be concurrently dirtying pages, and we + * might have synced a lot of newly appeared + * dirty pages, but have not synced all of the + * old dirty pages. + */ + done = 1; + break; } + if (wbc->nonblocking && bdi_write_congested(bdi)) { wbc->encountered_congestion = 1; done = 1; -- cgit From ab92661d5d9514647346047f30f67a7f35ffea67 Mon Sep 17 00:00:00 2001 From: Carsten Otte Date: Wed, 4 Feb 2009 15:12:16 -0800 Subject: do_wp_page: fix regression with execute in place Fix do_wp_page for VM_MIXEDMAP mappings. In the case where pfn_valid returns 0 for a pfn at the beginning of do_wp_page and the mapping is not shared writable, the code branches to label `gotten:' with old_page == NULL. In case the vma is locked (vma->vm_flags & VM_LOCKED), lock_page, clear_page_mlock, and unlock_page try to access the old_page. This patch checks whether old_page is valid before it is dereferenced. The regression was introduced by "mlock: mlocked pages are unevictable" (commit b291f000393f5a0b679012b39d79fbc85c018233). Signed-off-by: Carsten Otte Cc: Nick Piggin Cc: Heiko Carstens Cc: [2.6.28.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/memory.c b/mm/memory.c index 22bfa7a47a0b..baa999e87cd2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1999,7 +1999,7 @@ gotten: * Don't let another task, with possibly unlocked vma, * keep the mlocked page. */ - if (vma->vm_flags & VM_LOCKED) { + if ((vma->vm_flags & VM_LOCKED) && old_page) { lock_page(old_page); /* for LRU manipulation */ clear_page_mlock(old_page); unlock_page(old_page); -- cgit From d5b562330ec766292a3ac54ae5e0673610bd5b3d Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sun, 8 Feb 2009 20:56:58 +0000 Subject: mm: fix error case in mlock downgrade reversion Commit 27421e211a39784694b597dbf35848b88363c248, Manually revert "mlock: downgrade mmap sem while populating mlocked regions", has introduced its own regression: __mlock_vma_pages_range() may report an error (for example, -EFAULT from trying to lock down pages from beyond EOF), but mlock_vma_pages_range() must hide that from its callers as before. Reported-by: Sami Farin Signed-off-by: Hugh Dickins Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- mm/mlock.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/mlock.c b/mm/mlock.c index 028ec482fdd4..037161d61b4e 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -311,7 +311,10 @@ long mlock_vma_pages_range(struct vm_area_struct *vma, is_vm_hugetlb_page(vma) || vma == get_gate_vma(current))) { - return __mlock_vma_pages_range(vma, start, end, 1); + __mlock_vma_pages_range(vma, start, end, 1); + + /* Hide errors from mmap() and other callers */ + return 0; } /* -- cgit