| Message ID | 1405459752-7638-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index 123c79b..b56eb62 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -1525,8 +1525,7 @@ static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma, } wait_for_stable_page(page); - unlock_page(page); - return 0; + return VM_FAULT_LOCKED; out_unlock: unlock_page(page);
This is a note to let you know that I have just added a patch titled UBIFS: fix an mmap and fsync race condition to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11.5. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From f2573a2563a663c0562439ee543b1b67f58bf12b Mon Sep 17 00:00:00 2001 From: hujianyang <hujianyang@huawei.com> Date: Wed, 30 Apr 2014 14:06:06 +0800 Subject: UBIFS: fix an mmap and fsync race condition commit 691a7c6f28ac90cccd0dbcf81348ea90b211bdd0 upstream. There is a race condition in UBIFS: Thread A (mmap) Thread B (fsync) ->__do_fault ->write_cache_pages -> ubifs_vm_page_mkwrite -> budget_space -> lock_page -> release/convert_page_budget -> SetPagePrivate -> TestSetPageDirty -> unlock_page -> lock_page -> TestClearPageDirty -> ubifs_writepage -> do_writepage -> release_budget -> ClearPagePrivate -> unlock_page -> !(ret & VM_FAULT_LOCKED) -> lock_page -> set_page_dirty -> ubifs_set_page_dirty -> TestSetPageDirty (set page dirty without budgeting) -> unlock_page This leads to situation where we have a diry page but no budget allocated for this page, so further write-back may fail with -ENOSPC. In this fix we return from page_mkwrite without performing unlock_page. We return VM_FAULT_LOCKED instead. After doing this, the race above will not happen. Signed-off-by: hujianyang <hujianyang@huawei.com> Tested-by: Laurence Withers <lwithers@guralp.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/ubifs/file.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) -- 1.9.1