Subject: + mm-per-thread-vma-caching-fix-4.patch added to -mm tree To: davidlohr@xxxxxx,oleg@xxxxxxxxxx,riel@xxxxxxxxxx,torvalds@xxxxxxxxxxxxxxxxxxxx,walken@xxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Tue, 11 Mar 2014 11:58:11 -0700 The patch titled From: Davidlohr Bueso <davidlohr@xxxxxx> has been added to the -mm tree. Its filename is mm-per-thread-vma-caching-fix-4.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-per-thread-vma-caching-fix-4.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-per-thread-vma-caching-fix-4.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 *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Davidlohr Bueso <davidlohr@xxxxxx> Subject: mm,vmacache: also flush cache for VM_CLONE Oleg found that there is a potential race if we don't flush the task for threads (VM_CLONE): "Suppose we have a task T1 which has the valid vmacache, T1->vmacache_seqnum == T1->mm->vmacache_seqnum == 0. Suppose it sleeps a lot. Suppose that its subthread T2 does a lot munmap's, finally mm->vmacache_seqnum becomes zero again and T2 calls vmacache_flush_all(). T1 wakes up and does clone(CLONE_VM). The new thread T3 gets the copy of T2's ->vmacache_seqnum and ->vmacache[]. T2 continues, vmacache_flush_all() finds T1 and does vmacache_flush(T1). But the new thread T3 is not on the list yet, vmacache_flush_all() can't find it. So T3 will run with vmacache_valid() == T (till the next invalidate(mm) of course) but its ->vmacache[] points to nowhere." Address this by moving the flush call into copy_mm(), instead of only having it in dup_mm(). Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Michel Lespinasse <walken@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/fork.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff -puN kernel/fork.c~mm-per-thread-vma-caching-fix-4 kernel/fork.c --- a/kernel/fork.c~mm-per-thread-vma-caching-fix-4 +++ a/kernel/fork.c @@ -840,9 +840,6 @@ static struct mm_struct *dup_mm(struct t if (mm->binfmt && !try_module_get(mm->binfmt->module)) goto free_pt; - /* initialize the new vmacache entries */ - vmacache_flush(tsk); - return mm; free_pt: @@ -886,6 +883,9 @@ static int copy_mm(unsigned long clone_f if (!oldmm) return 0; + /* initialize the new vmacache entries */ + vmacache_flush(tsk); + if (clone_flags & CLONE_VM) { atomic_inc(&oldmm->mm_users); mm = oldmm; _ Patches currently in -mm which might be from davidlohr@xxxxxx are origin.patch mm-hugetlb-unify-region-structure-handling.patch mm-hugetlb-improve-cleanup-resv_map-parameters.patch mm-hugetlb-fix-race-in-region-tracking.patch mm-hugetlb-remove-resv_map_put.patch mm-hugetlb-use-vma_resv_map-map-types.patch mm-hugetlb-improve-page-fault-scalability.patch mm-hugetlb-improve-page-fault-scalability-fix.patch mm-hugetlb-mark-some-bootstrap-functions-as-__init.patch mm-memoryc-update-comment-in-unmap_single_vma.patch mm-per-thread-vma-caching.patch mm-per-thread-vma-caching-fix-3.patch mm-per-thread-vma-caching-fix-4.patch ipccompat-remove-sc_semopm-macro.patch ipc-use-device_initcall.patch linux-next.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