Subject: [folded-merged] mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags-ignore-madv_hugepage-on-s390-to-prevent-sigsegv-in-qemu.patch removed from -mm tree
To: athorlton@xxxxxxx,aarcange@xxxxxxxxxx,borntraeger@xxxxxxxxxx,ebiederm@xxxxxxxxxxxx,gerald.schaefer@xxxxxxxxxx,heiko.carstens@xxxxxxxxxx,kirill.shutemov@xxxxxxxxxxxxxxx,mgorman@xxxxxxx,mingo@xxxxxxxxxx,oleg@xxxxxxxxxx,pbonzini@xxxxxxxxxx,peterz@xxxxxxxxxxxxx,riel@xxxxxxxxxx,rientjes@xxxxxxxxxx,schwidefsky@xxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 07 Apr 2014 14:58:08 -0700
The patch titled
Subject: mm, s390: ignore MADV_HUGEPAGE on s390 to prevent SIGSEGV in qemu
has been removed from the -mm tree. Its filename was
mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags-ignore-madv_hugepage-on-s390-to-prevent-sigsegv-in-qemu.patch
This patch was dropped because it was folded into mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags.patch
------------------------------------------------------
From: Alex Thorlton <athorlton@xxxxxxx>
Subject: mm, s390: ignore MADV_HUGEPAGE on s390 to prevent SIGSEGV in qemu
As Christian pointed out, the recent 'Revert "thp: make MADV_HUGEPAGE
check for mm->def_flags"' breaks qemu, it does QEMU_MADV_HUGEPAGE for all
kvm pages but this doesn't work after s390_enable_sie/thp_split_mm.
Paolo suggested that instead of failing on the call to madvise, we simply
ignore the call (return 0).
Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Suggested-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Alex Thorlton <athorlton@xxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Tested-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN mm/huge_memory.c~mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags-ignore-madv_hugepage-on-s390-to-prevent-sigsegv-in-qemu mm/huge_memory.c
--- a/mm/huge_memory.c~mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags-ignore-madv_hugepage-on-s390-to-prevent-sigsegv-in-qemu
+++ a/mm/huge_memory.c
@@ -1893,6 +1893,15 @@ int hugepage_madvise(struct vm_area_stru
{
switch (advice) {
case MADV_HUGEPAGE:
+#ifdef CONFIG_S390
+ /*
+ * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
+ * can't handle this properly after s390_enable_sie, so we simply
+ * ignore the madvise to prevent qemu from causing a SIGSEGV.
+ */
+ if (mm_has_pgste(vma->vm_mm))
+ return 0;
+#endif
/*
* Be somewhat over-protective like KSM for now!
*/
_
Patches currently in -mm which might be from athorlton@xxxxxxx are
mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags.patch
mm-thp-add-vm_init_def_mask-and-prctl_thp_disable.patch
exec-kill-the-unnecessary-mm-def_flags-setting-in-load_elf_binary.patch
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