As reported, ever since commit 1013af4f585f ("mm/hugetlb: fix
huge_pmd_unshare() vs GUP-fast race") we can end up in some situations
where we perform so many IPI broadcasts when unsharing hugetlb PMD page
tables that it severely regresses some workloads.
In particular, when we fork()+exit(), or when we munmap() a large
area backed by many shared PMD tables, we perform one IPI broadcast per
unshared PMD table.
There are two optimizations to be had:
(1) When we process (unshare) multiple such PMD tables, such as during
exit(), it is sufficient to send a single IPI broadcast (as long as
we respect locking rules) instead of one per PMD table.
Locking prevents that any of these PMD tables could get reused before
we drop the lock.
(2) When we are not the last sharer (> 2 users including us), there is
no need to send the IPI broadcast. The shared PMD tables cannot
become exclusive (fully unshared) before an IPI will be broadcasted
by the last sharer.
Concurrent GUP-fast could walk into a PMD table just before we
unshared it. It could then succeed in grabbing a page from the
shared page table even after munmap() etc succeeded (and supressed
an IPI). But there is not difference compared to GUP-fast just
sleeping for a while after grabbing the page and re-enabling IRQs.
Most importantly, GUP-fast will never walk into page tables that are
no-longer shared, because the last sharer will issue an IPI
broadcast.
(if ever required, checking whether the PUD changed in GUP-fast
after grabbing the page like we do in the PTE case could handle
this)
So let's rework PMD sharing TLB flushing + IPI sync to use the mmu_gather
infrastructure so we can implement these optimizations and demystify the
code at least a bit. Extend the mmu_gather infrastructure to be able to
deal with our special hugetlb PMD table sharing implementation.
To make initialization of the mmu_gather easier when working on a single
VMA (in particular, when dealing with hugetlb), provide
tlb_gather_mmu_vma().
We'll consolidate the handling for (full) unsharing of PMD tables in
tlb_unshare_pmd_ptdesc() and tlb_flush_unshared_tables(), and track
in "struct mmu_gather" whether we had (full) unsharing of PMD tables.
Because locking is very special (concurrent unsharing+reuse must be
prevented), we disallow deferring flushing to tlb_finish_mmu() and instead
require an explicit earlier call to tlb_flush_unshared_tables().
From hugetlb code, we call huge_pmd_unshare_flush() where we make sure
that the expected lock protecting us from concurrent unsharing+reuse is
still held.
Check with a VM_WARN_ON_ONCE() in tlb_finish_mmu() that
tlb_flush_unshared_tables() was properly called earlier.
Document it all properly.
Notes about tlb_remove_table_sync_one() interaction with unsharing:
There are two fairly tricky things:
(1) tlb_remove_table_sync_one() is a NOP on architectures without
CONFIG_MMU_GATHER_RCU_TABLE_FREE.
Here, the assumption is that the previous TLB flush would send an
IPI to all relevant CPUs. Careful: some architectures like x86 only
send IPIs to all relevant CPUs when tlb->freed_tables is set.
The relevant architectures should be selecting
MMU_GATHER_RCU_TABLE_FREE, but x86 might not do that in stable
kernels and it might have been problematic before this patch.
Also, the arch flushing behavior (independent of IPIs) is different
when tlb->freed_tables is set. Do we have to enlighten them to also
take care of tlb->unshared_tables? So far we didn't care, so
hopefully we are fine. Of course, we could be setting
tlb->freed_tables as well, but that might then unnecessarily flush
too much, because the semantics of tlb->freed_tables are a bit
fuzzy.
This patch changes nothing in this regard.
(2) tlb_remove_table_sync_one() is not a NOP on architectures with
CONFIG_MMU_GATHER_RCU_TABLE_FREE that actually don't need a sync.
Take x86 as an example: in the common case (!pv, !X86_FEATURE_INVLPGB)
we still issue IPIs during TLB flushes and don't actually need the
second tlb_remove_table_sync_one().
This optimized can be implemented on top of this, by checking e.g., in
tlb_remove_table_sync_one() whether we really need IPIs. But as
described in (1), it really must honor tlb->freed_tables then to
send IPIs to all relevant CPUs.
Notes on TLB flushing changes:
(1) Flushing for non-shared PMD tables
We're converting from flush_hugetlb_tlb_range() to
tlb_remove_huge_tlb_entry(). Given that we properly initialize the
MMU gather in tlb_gather_mmu_vma() to be hugetlb aware, similar to
__unmap_hugepage_range(), that should be fine.
(2) Flushing for shared PMD tables
We're converting from various things (flush_hugetlb_tlb_range(),
tlb_flush_pmd_range(), flush_tlb_range()) to tlb_flush_pmd_range().
tlb_flush_pmd_range() achieves the same that
tlb_remove_huge_tlb_entry() would achieve in these scenarios.
Note that tlb_remove_huge_tlb_entry() also calls
__tlb_remove_tlb_entry(), however that is only implemented on
powerpc, which does not support PMD table sharing.
Similar to (1), tlb_gather_mmu_vma() should make sure that TLB
flushing keeps on working as expected.
Further, note that the ptdesc_pmd_pts_dec() in huge_pmd_share() is not a
concern, as we are holding the i_mmap_lock the whole time, preventing
concurrent unsharing. That ptdesc_pmd_pts_dec() usage will be removed
separately as a cleanup later.
There are plenty more cleanups to be had, but they have to wait until
this is fixed.
Fixes: 1013af4f585f ("mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race")
Reported-by: Uschakow, Stanislav" <suschako(a)amazon.de>
Closes: https://lore.kernel.org/all/4d3878531c76479d9f8ca9789dc6485d@amazon.de/
Tested-by: Laurence Oberman <loberman(a)redhat.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: David Hildenbrand (Red Hat) <david(a)kernel.org>
---
include/asm-generic/tlb.h | 77 +++++++++++++++++++++++-
include/linux/hugetlb.h | 15 +++--
include/linux/mm_types.h | 1 +
mm/hugetlb.c | 123 ++++++++++++++++++++++----------------
mm/mmu_gather.c | 33 ++++++++++
mm/rmap.c | 25 +++++---
6 files changed, 208 insertions(+), 66 deletions(-)
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 1fff717cae510..4d679d2a206b4 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -46,7 +46,8 @@
*
* The mmu_gather API consists of:
*
- * - tlb_gather_mmu() / tlb_gather_mmu_fullmm() / tlb_finish_mmu()
+ * - tlb_gather_mmu() / tlb_gather_mmu_fullmm() / tlb_gather_mmu_vma() /
+ * tlb_finish_mmu()
*
* start and finish a mmu_gather
*
@@ -364,6 +365,20 @@ struct mmu_gather {
unsigned int vma_huge : 1;
unsigned int vma_pfn : 1;
+ /*
+ * Did we unshare (unmap) any shared page tables? For now only
+ * used for hugetlb PMD table sharing.
+ */
+ unsigned int unshared_tables : 1;
+
+ /*
+ * Did we unshare any page tables such that they are now exclusive
+ * and could get reused+modified by the new owner? When setting this
+ * flag, "unshared_tables" will be set as well. For now only used
+ * for hugetlb PMD table sharing.
+ */
+ unsigned int fully_unshared_tables : 1;
+
unsigned int batch_count;
#ifndef CONFIG_MMU_GATHER_NO_GATHER
@@ -400,6 +415,7 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
tlb->cleared_pmds = 0;
tlb->cleared_puds = 0;
tlb->cleared_p4ds = 0;
+ tlb->unshared_tables = 0;
/*
* Do not reset mmu_gather::vma_* fields here, we do not
* call into tlb_start_vma() again to set them if there is an
@@ -484,7 +500,7 @@ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
* these bits.
*/
if (!(tlb->freed_tables || tlb->cleared_ptes || tlb->cleared_pmds ||
- tlb->cleared_puds || tlb->cleared_p4ds))
+ tlb->cleared_puds || tlb->cleared_p4ds || tlb->unshared_tables))
return;
tlb_flush(tlb);
@@ -773,6 +789,63 @@ static inline bool huge_pmd_needs_flush(pmd_t oldpmd, pmd_t newpmd)
}
#endif
+#ifdef CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING
+static inline void tlb_unshare_pmd_ptdesc(struct mmu_gather *tlb, struct ptdesc *pt,
+ unsigned long addr)
+{
+ /*
+ * The caller must make sure that concurrent unsharing + exclusive
+ * reuse is impossible until tlb_flush_unshared_tables() was called.
+ */
+ VM_WARN_ON_ONCE(!ptdesc_pmd_is_shared(pt));
+ ptdesc_pmd_pts_dec(pt);
+
+ /* Clearing a PUD pointing at a PMD table with PMD leaves. */
+ tlb_flush_pmd_range(tlb, addr & PUD_MASK, PUD_SIZE);
+
+ /*
+ * If the page table is now exclusively owned, we fully unshared
+ * a page table.
+ */
+ if (!ptdesc_pmd_is_shared(pt))
+ tlb->fully_unshared_tables = true;
+ tlb->unshared_tables = true;
+}
+
+static inline void tlb_flush_unshared_tables(struct mmu_gather *tlb)
+{
+ /*
+ * As soon as the caller drops locks to allow for reuse of
+ * previously-shared tables, these tables could get modified and
+ * even reused outside of hugetlb context, so we have to make sure that
+ * any page table walkers (incl. TLB, GUP-fast) are aware of that
+ * change.
+ *
+ * Even if we are not fully unsharing a PMD table, we must
+ * flush the TLB for the unsharer now.
+ */
+ if (tlb->unshared_tables)
+ tlb_flush_mmu_tlbonly(tlb);
+
+ /*
+ * Similarly, we must make sure that concurrent GUP-fast will not
+ * walk previously-shared page tables that are getting modified+reused
+ * elsewhere. So broadcast an IPI to wait for any concurrent GUP-fast.
+ *
+ * We only perform this when we are the last sharer of a page table,
+ * as the IPI will reach all CPUs: any GUP-fast.
+ *
+ * Note that on configs where tlb_remove_table_sync_one() is a NOP,
+ * the expectation is that the tlb_flush_mmu_tlbonly() would have issued
+ * required IPIs already for us.
+ */
+ if (tlb->fully_unshared_tables) {
+ tlb_remove_table_sync_one();
+ tlb->fully_unshared_tables = false;
+ }
+}
+#endif /* CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING */
+
#endif /* CONFIG_MMU */
#endif /* _ASM_GENERIC__TLB_H */
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 03c8725efa289..e51b8ef0cebd9 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -240,8 +240,9 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
pte_t *huge_pte_offset(struct mm_struct *mm,
unsigned long addr, unsigned long sz);
unsigned long hugetlb_mask_last_page(struct hstate *h);
-int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep);
+int huge_pmd_unshare(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep);
+void huge_pmd_unshare_flush(struct mmu_gather *tlb, struct vm_area_struct *vma);
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
unsigned long *start, unsigned long *end);
@@ -300,13 +301,17 @@ static inline struct address_space *hugetlb_folio_mapping_lock_write(
return NULL;
}
-static inline int huge_pmd_unshare(struct mm_struct *mm,
- struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep)
+static inline int huge_pmd_unshare(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
{
return 0;
}
+static inline void huge_pmd_unshare_flush(struct mmu_gather *tlb,
+ struct vm_area_struct *vma)
+{
+}
+
static inline void adjust_range_if_pmd_sharing_possible(
struct vm_area_struct *vma,
unsigned long *start, unsigned long *end)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 42af2292951d4..d1053b2c1f800 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1522,6 +1522,7 @@ static inline unsigned int mm_cid_size(void)
struct mmu_gather;
extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm);
extern void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm);
+void tlb_gather_mmu_vma(struct mmu_gather *tlb, struct vm_area_struct *vma);
extern void tlb_finish_mmu(struct mmu_gather *tlb);
struct vm_fault;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3c77cdef12a32..2609b6d58f99e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5096,7 +5096,7 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
unsigned long last_addr_mask;
pte_t *src_pte, *dst_pte;
struct mmu_notifier_range range;
- bool shared_pmd = false;
+ struct mmu_gather tlb;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, old_addr,
old_end);
@@ -5106,6 +5106,7 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
* range.
*/
flush_cache_range(vma, range.start, range.end);
+ tlb_gather_mmu_vma(&tlb, vma);
mmu_notifier_invalidate_range_start(&range);
last_addr_mask = hugetlb_mask_last_page(h);
@@ -5122,8 +5123,7 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
if (huge_pte_none(huge_ptep_get(mm, old_addr, src_pte)))
continue;
- if (huge_pmd_unshare(mm, vma, old_addr, src_pte)) {
- shared_pmd = true;
+ if (huge_pmd_unshare(&tlb, vma, old_addr, src_pte)) {
old_addr |= last_addr_mask;
new_addr |= last_addr_mask;
continue;
@@ -5134,15 +5134,16 @@ int move_hugetlb_page_tables(struct vm_area_struct *vma,
break;
move_huge_pte(vma, old_addr, new_addr, src_pte, dst_pte, sz);
+ tlb_remove_huge_tlb_entry(h, &tlb, src_pte, old_addr);
}
- if (shared_pmd)
- flush_hugetlb_tlb_range(vma, range.start, range.end);
- else
- flush_hugetlb_tlb_range(vma, old_end - len, old_end);
+ tlb_flush_mmu_tlbonly(&tlb);
+ huge_pmd_unshare_flush(&tlb, vma);
+
mmu_notifier_invalidate_range_end(&range);
i_mmap_unlock_write(mapping);
hugetlb_vma_unlock_write(vma);
+ tlb_finish_mmu(&tlb);
return len + old_addr - old_end;
}
@@ -5161,7 +5162,6 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
unsigned long sz = huge_page_size(h);
bool adjust_reservation;
unsigned long last_addr_mask;
- bool force_flush = false;
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~huge_page_mask(h));
@@ -5184,10 +5184,8 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
}
ptl = huge_pte_lock(h, mm, ptep);
- if (huge_pmd_unshare(mm, vma, address, ptep)) {
+ if (huge_pmd_unshare(tlb, vma, address, ptep)) {
spin_unlock(ptl);
- tlb_flush_pmd_range(tlb, address & PUD_MASK, PUD_SIZE);
- force_flush = true;
address |= last_addr_mask;
continue;
}
@@ -5303,14 +5301,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
}
tlb_end_vma(tlb, vma);
- /*
- * There is nothing protecting a previously-shared page table that we
- * unshared through huge_pmd_unshare() from getting freed after we
- * release i_mmap_rwsem, so flush the TLB now. If huge_pmd_unshare()
- * succeeded, flush the range corresponding to the pud.
- */
- if (force_flush)
- tlb_flush_mmu_tlbonly(tlb);
+ huge_pmd_unshare_flush(tlb, vma);
}
void __hugetlb_zap_begin(struct vm_area_struct *vma,
@@ -6409,11 +6400,11 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
pte_t pte;
struct hstate *h = hstate_vma(vma);
long pages = 0, psize = huge_page_size(h);
- bool shared_pmd = false;
struct mmu_notifier_range range;
unsigned long last_addr_mask;
bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
+ struct mmu_gather tlb;
/*
* In the case of shared PMDs, the area to flush could be beyond
@@ -6426,6 +6417,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
BUG_ON(address >= end);
flush_cache_range(vma, range.start, range.end);
+ tlb_gather_mmu_vma(&tlb, vma);
mmu_notifier_invalidate_range_start(&range);
hugetlb_vma_lock_write(vma);
@@ -6452,7 +6444,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
}
}
ptl = huge_pte_lock(h, mm, ptep);
- if (huge_pmd_unshare(mm, vma, address, ptep)) {
+ if (huge_pmd_unshare(&tlb, vma, address, ptep)) {
/*
* When uffd-wp is enabled on the vma, unshare
* shouldn't happen at all. Warn about it if it
@@ -6461,7 +6453,6 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
WARN_ON_ONCE(uffd_wp || uffd_wp_resolve);
pages++;
spin_unlock(ptl);
- shared_pmd = true;
address |= last_addr_mask;
continue;
}
@@ -6522,22 +6513,16 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
pte = huge_pte_clear_uffd_wp(pte);
huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte);
pages++;
+ tlb_remove_huge_tlb_entry(h, &tlb, ptep, address);
}
next:
spin_unlock(ptl);
cond_resched();
}
- /*
- * There is nothing protecting a previously-shared page table that we
- * unshared through huge_pmd_unshare() from getting freed after we
- * release i_mmap_rwsem, so flush the TLB now. If huge_pmd_unshare()
- * succeeded, flush the range corresponding to the pud.
- */
- if (shared_pmd)
- flush_hugetlb_tlb_range(vma, range.start, range.end);
- else
- flush_hugetlb_tlb_range(vma, start, end);
+
+ tlb_flush_mmu_tlbonly(&tlb);
+ huge_pmd_unshare_flush(&tlb, vma);
/*
* No need to call mmu_notifier_arch_invalidate_secondary_tlbs() we are
* downgrading page table protection not changing it to point to a new
@@ -6548,6 +6533,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
i_mmap_unlock_write(vma->vm_file->f_mapping);
hugetlb_vma_unlock_write(vma);
mmu_notifier_invalidate_range_end(&range);
+ tlb_finish_mmu(&tlb);
return pages > 0 ? (pages << h->order) : pages;
}
@@ -6904,18 +6890,27 @@ pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
return pte;
}
-/*
- * unmap huge page backed by shared pte.
+/**
+ * huge_pmd_unshare - Unmap a pmd table if it is shared by multiple users
+ * @tlb: the current mmu_gather.
+ * @vma: the vma covering the pmd table.
+ * @addr: the address we are trying to unshare.
+ * @ptep: pointer into the (pmd) page table.
+ *
+ * Called with the page table lock held, the i_mmap_rwsem held in write mode
+ * and the hugetlb vma lock held in write mode.
*
- * Called with page table lock held.
+ * Note: The caller must call huge_pmd_unshare_flush() before dropping the
+ * i_mmap_rwsem.
*
- * returns: 1 successfully unmapped a shared pte page
- * 0 the underlying pte page is not shared, or it is the last user
+ * Returns: 1 if it was a shared PMD table and it got unmapped, or 0 if it
+ * was not a shared PMD table.
*/
-int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep)
+int huge_pmd_unshare(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep)
{
unsigned long sz = huge_page_size(hstate_vma(vma));
+ struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd = pgd_offset(mm, addr);
p4d_t *p4d = p4d_offset(pgd, addr);
pud_t *pud = pud_offset(p4d, addr);
@@ -6927,18 +6922,36 @@ int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
i_mmap_assert_write_locked(vma->vm_file->f_mapping);
hugetlb_vma_assert_locked(vma);
pud_clear(pud);
- /*
- * Once our caller drops the rmap lock, some other process might be
- * using this page table as a normal, non-hugetlb page table.
- * Wait for pending gup_fast() in other threads to finish before letting
- * that happen.
- */
- tlb_remove_table_sync_one();
- ptdesc_pmd_pts_dec(virt_to_ptdesc(ptep));
+
+ tlb_unshare_pmd_ptdesc(tlb, virt_to_ptdesc(ptep), addr);
+
mm_dec_nr_pmds(mm);
return 1;
}
+/*
+ * huge_pmd_unshare_flush - Complete a sequence of huge_pmd_unshare() calls
+ * @tlb: the current mmu_gather.
+ * @vma: the vma covering the pmd table.
+ *
+ * Perform necessary TLB flushes or IPI broadcasts to synchronize PMD table
+ * unsharing with concurrent page table walkers.
+ *
+ * This function must be called after a sequence of huge_pmd_unshare()
+ * calls while still holding the i_mmap_rwsem.
+ */
+void huge_pmd_unshare_flush(struct mmu_gather *tlb, struct vm_area_struct *vma)
+{
+ /*
+ * We must synchronize page table unsharing such that nobody will
+ * try reusing a previously-shared page table while it might still
+ * be in use by previous sharers (TLB, GUP_fast).
+ */
+ i_mmap_assert_write_locked(vma->vm_file->f_mapping);
+
+ tlb_flush_unshared_tables(tlb);
+}
+
#else /* !CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING */
pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -6947,12 +6960,16 @@ pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
return NULL;
}
-int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep)
+int huge_pmd_unshare(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep)
{
return 0;
}
+void huge_pmd_unshare_flush(struct mmu_gather *tlb, struct vm_area_struct *vma)
+{
+}
+
void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
unsigned long *start, unsigned long *end)
{
@@ -7219,6 +7236,7 @@ static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
unsigned long sz = huge_page_size(h);
struct mm_struct *mm = vma->vm_mm;
struct mmu_notifier_range range;
+ struct mmu_gather tlb;
unsigned long address;
spinlock_t *ptl;
pte_t *ptep;
@@ -7230,6 +7248,8 @@ static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
return;
flush_cache_range(vma, start, end);
+ tlb_gather_mmu_vma(&tlb, vma);
+
/*
* No need to call adjust_range_if_pmd_sharing_possible(), because
* we have already done the PUD_SIZE alignment.
@@ -7248,10 +7268,10 @@ static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
if (!ptep)
continue;
ptl = huge_pte_lock(h, mm, ptep);
- huge_pmd_unshare(mm, vma, address, ptep);
+ huge_pmd_unshare(&tlb, vma, address, ptep);
spin_unlock(ptl);
}
- flush_hugetlb_tlb_range(vma, start, end);
+ huge_pmd_unshare_flush(&tlb, vma);
if (take_locks) {
i_mmap_unlock_write(vma->vm_file->f_mapping);
hugetlb_vma_unlock_write(vma);
@@ -7261,6 +7281,7 @@ static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
* Documentation/mm/mmu_notifier.rst.
*/
mmu_notifier_invalidate_range_end(&range);
+ tlb_finish_mmu(&tlb);
}
/*
diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c
index 247e3f9db6c7a..cd32c2dbf501b 100644
--- a/mm/mmu_gather.c
+++ b/mm/mmu_gather.c
@@ -10,6 +10,7 @@
#include <linux/swap.h>
#include <linux/rmap.h>
#include <linux/pgalloc.h>
+#include <linux/hugetlb.h>
#include <asm/tlb.h>
@@ -426,6 +427,7 @@ static void __tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
#endif
tlb->vma_pfn = 0;
+ tlb->fully_unshared_tables = 0;
__tlb_reset_range(tlb);
inc_tlb_flush_pending(tlb->mm);
}
@@ -459,6 +461,31 @@ void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm)
__tlb_gather_mmu(tlb, mm, true);
}
+/**
+ * tlb_gather_mmu - initialize an mmu_gather structure for operating on a single
+ * VMA
+ * @tlb: the mmu_gather structure to initialize
+ * @vma: the vm_area_struct
+ *
+ * Called to initialize an (on-stack) mmu_gather structure for operating on
+ * a single VMA. In contrast to tlb_gather_mmu(), calling this function will
+ * not require another call to tlb_start_vma(). In contrast to tlb_start_vma(),
+ * this function will *not* call flush_cache_range().
+ *
+ * For hugetlb VMAs, this function will also initialize the mmu_gather
+ * page_size accordingly, not requiring a separate call to
+ * tlb_change_page_size().
+ *
+ */
+void tlb_gather_mmu_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
+{
+ tlb_gather_mmu(tlb, vma->vm_mm);
+ tlb_update_vma_flags(tlb, vma);
+ if (is_vm_hugetlb_page(vma))
+ /* All entries have the same size. */
+ tlb_change_page_size(tlb, huge_page_size(hstate_vma(vma)));
+}
+
/**
* tlb_finish_mmu - finish an mmu_gather structure
* @tlb: the mmu_gather structure to finish
@@ -468,6 +495,12 @@ void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm)
*/
void tlb_finish_mmu(struct mmu_gather *tlb)
{
+ /*
+ * We expect an earlier huge_pmd_unshare_flush() call to sort this out,
+ * due to complicated locking requirements with page table unsharing.
+ */
+ VM_WARN_ON_ONCE(tlb->fully_unshared_tables);
+
/*
* If there are parallel threads are doing PTE changes on same range
* under non-exclusive lock (e.g., mmap_lock read-side) but defer TLB
diff --git a/mm/rmap.c b/mm/rmap.c
index 748f48727a162..7b9879ef442d9 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -76,7 +76,7 @@
#include <linux/mm_inline.h>
#include <linux/oom.h>
-#include <asm/tlbflush.h>
+#include <asm/tlb.h>
#define CREATE_TRACE_POINTS
#include <trace/events/migrate.h>
@@ -2008,13 +2008,17 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
* if unsuccessful.
*/
if (!anon) {
+ struct mmu_gather tlb;
+
VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
if (!hugetlb_vma_trylock_write(vma))
goto walk_abort;
- if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) {
+
+ tlb_gather_mmu_vma(&tlb, vma);
+ if (huge_pmd_unshare(&tlb, vma, address, pvmw.pte)) {
hugetlb_vma_unlock_write(vma);
- flush_tlb_range(vma,
- range.start, range.end);
+ huge_pmd_unshare_flush(&tlb, vma);
+ tlb_finish_mmu(&tlb);
/*
* The PMD table was unmapped,
* consequently unmapping the folio.
@@ -2022,6 +2026,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
goto walk_done;
}
hugetlb_vma_unlock_write(vma);
+ tlb_finish_mmu(&tlb);
}
pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
if (pte_dirty(pteval))
@@ -2398,17 +2403,20 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
* fail if unsuccessful.
*/
if (!anon) {
+ struct mmu_gather tlb;
+
VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
if (!hugetlb_vma_trylock_write(vma)) {
page_vma_mapped_walk_done(&pvmw);
ret = false;
break;
}
- if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) {
- hugetlb_vma_unlock_write(vma);
- flush_tlb_range(vma,
- range.start, range.end);
+ tlb_gather_mmu_vma(&tlb, vma);
+ if (huge_pmd_unshare(&tlb, vma, address, pvmw.pte)) {
+ hugetlb_vma_unlock_write(vma);
+ huge_pmd_unshare_flush(&tlb, vma);
+ tlb_finish_mmu(&tlb);
/*
* The PMD table was unmapped,
* consequently unmapping the folio.
@@ -2417,6 +2425,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
break;
}
hugetlb_vma_unlock_write(vma);
+ tlb_finish_mmu(&tlb);
}
/* Nuke the hugetlb page table entry */
pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
--
2.52.0
Commit 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error path")
was merged in 6.11 and then backported to stable trees through 5.10. It
relocates the line that initializes the variable 'child' to a later
point in spi_byte_probe().
Versions < 6.9 do not have commit ccc35ff2fd29 ("leds: spi-byte: Use
devm_led_classdev_register_ext()"), which removes a line that reads a
property from 'child' before its new initialization point. Consequently,
spi_byte_probe() reads from an uninitialized device node in stable
kernels 6.6-5.10.
Initialize 'child' before it is first accessed.
Fixes: 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error path")
Signed-off-by: Tiffany Yang <ynaffit(a)google.com>
---
As an alternative to moving the initialization of 'child' up,
Fedor Pchelkin proposed [1] backporting the change that removes the
intermediate access.
[1] https://lore.kernel.org/stable/20241029204128.527033-1-pchelkin@ispras.ru/
---
drivers/leds/leds-spi-byte.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/leds/leds-spi-byte.c b/drivers/leds/leds-spi-byte.c
index afe9bff7c7c1..4520df1e2341 100644
--- a/drivers/leds/leds-spi-byte.c
+++ b/drivers/leds/leds-spi-byte.c
@@ -96,6 +96,7 @@ static int spi_byte_probe(struct spi_device *spi)
if (!led)
return -ENOMEM;
+ child = of_get_next_available_child(dev_of_node(dev), NULL);
of_property_read_string(child, "label", &name);
strscpy(led->name, name, sizeof(led->name));
led->spi = spi;
@@ -106,7 +107,6 @@ static int spi_byte_probe(struct spi_device *spi)
led->ldev.max_brightness = led->cdef->max_value - led->cdef->off_value;
led->ldev.brightness_set_blocking = spi_byte_brightness_set_blocking;
- child = of_get_next_available_child(dev_of_node(dev), NULL);
state = of_get_property(child, "default-state", NULL);
if (state) {
if (!strcmp(state, "on")) {
--
2.52.0.351.gbe84eed79e-goog
The patch titled
Subject: x86/kexec: add a sanity check on previous kernel's ima kexec buffer
has been added to the -mm mm-nonmm-unstable branch. Its filename is
x86-kexec-add-a-sanity-check-on-previous-kernels-ima-kexec-buffer.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Subject: x86/kexec: add a sanity check on previous kernel's ima kexec buffer
Date: Mon, 29 Dec 2025 00:15:23 -0800
When the second-stage kernel is booted via kexec with a limiting command
line such as "mem=<size>", the physical range that contains the carried
over IMA measurement list may fall outside the truncated RAM leading to a
kernel panic.
BUG: unable to handle page fault for address: ffff97793ff47000
RIP: ima_restore_measurement_list+0xdc/0x45a
#PF: error_code(0x0000) ��� not-present page
Other architectures already validate the range with page_is_ram(), as done
in commit cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer
against memory bounds") do a similar check on x86.
Without carrying the measurement list across kexec, the attestation would
fail.
Link: https://lkml.kernel.org/r/20251229081523.622515-4-harshit.m.mogalapalli@ora…
Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Reported-by: Paul Webb <paul.x.webb(a)oracle.com>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Ard Biesheuvel <ardb(a)kernel.org>
Cc: Borislav Betkov <bp(a)alien8.de>
Cc: guoweikang <guoweikang.kernel(a)gmail.com>
Cc: Henry Willard <henry.willard(a)oracle.com>
Cc: "H. Peter Anvin" <hpa(a)zytor.com>
Cc: Ingo Molnar <mingo(a)redhat.com>
Cc: Jiri Bohac <jbohac(a)suse.cz>
Cc: Joel Granados <joel.granados(a)kernel.org>
Cc: Jonathan McDowell <noodles(a)fb.com>
Cc: Mike Rapoport <rppt(a)kernel.org>
Cc: Mimi Zohar <zohar(a)linux.ibm.com>
Cc: Sohil Mehta <sohil.mehta(a)intel.com>
Cc: Sourabh Jain <sourabhjain(a)linux.ibm.com>
Cc: Thomas Gleinxer <tglx(a)linutronix.de>
Cc: Yifei Liu <yifei.l.liu(a)oracle.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
arch/x86/kernel/setup.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/arch/x86/kernel/setup.c~x86-kexec-add-a-sanity-check-on-previous-kernels-ima-kexec-buffer
+++ a/arch/x86/kernel/setup.c
@@ -439,9 +439,15 @@ int __init ima_free_kexec_buffer(void)
int __init ima_get_kexec_buffer(void **addr, size_t *size)
{
+ int ret;
+
if (!ima_kexec_buffer_size)
return -ENOENT;
+ ret = ima_validate_range(ima_kexec_buffer_phys, ima_kexec_buffer_size);
+ if (ret)
+ return ret;
+
*addr = __va(ima_kexec_buffer_phys);
*size = ima_kexec_buffer_size;
_
Patches currently in -mm which might be from harshit.m.mogalapalli(a)oracle.com are
ima-add-ima_validate_range-for-previous-kernel-ima-buffer.patch
of-kexec-refactor-ima_get_kexec_buffer-to-use-ima_validate_range.patch
x86-kexec-add-a-sanity-check-on-previous-kernels-ima-kexec-buffer.patch
The patch titled
Subject: of/kexec: refactor ima_get_kexec_buffer() to use ima_validate_range()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
of-kexec-refactor-ima_get_kexec_buffer-to-use-ima_validate_range.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Subject: of/kexec: refactor ima_get_kexec_buffer() to use ima_validate_range()
Date: Mon, 29 Dec 2025 00:15:22 -0800
Refactor the OF/DT ima_get_kexec_buffer() to use a generic helper to
validate the address range. No functional change intended.
Link: https://lkml.kernel.org/r/20251229081523.622515-3-harshit.m.mogalapalli@ora…
Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Ard Biesheuvel <ardb(a)kernel.org>
Cc: Borislav Betkov <bp(a)alien8.de>
Cc: guoweikang <guoweikang.kernel(a)gmail.com>
Cc: Henry Willard <henry.willard(a)oracle.com>
Cc: "H. Peter Anvin" <hpa(a)zytor.com>
Cc: Ingo Molnar <mingo(a)redhat.com>
Cc: Jiri Bohac <jbohac(a)suse.cz>
Cc: Joel Granados <joel.granados(a)kernel.org>
Cc: Jonathan McDowell <noodles(a)fb.com>
Cc: Mike Rapoport <rppt(a)kernel.org>
Cc: Mimi Zohar <zohar(a)linux.ibm.com>
Cc: Paul Webb <paul.x.webb(a)oracle.com>
Cc: Sohil Mehta <sohil.mehta(a)intel.com>
Cc: Sourabh Jain <sourabhjain(a)linux.ibm.com>
Cc: Thomas Gleinxer <tglx(a)linutronix.de>
Cc: Yifei Liu <yifei.l.liu(a)oracle.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
drivers/of/kexec.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)
--- a/drivers/of/kexec.c~of-kexec-refactor-ima_get_kexec_buffer-to-use-ima_validate_range
+++ a/drivers/of/kexec.c
@@ -128,7 +128,6 @@ int __init ima_get_kexec_buffer(void **a
{
int ret, len;
unsigned long tmp_addr;
- unsigned long start_pfn, end_pfn;
size_t tmp_size;
const void *prop;
@@ -144,17 +143,9 @@ int __init ima_get_kexec_buffer(void **a
if (!tmp_size)
return -ENOENT;
- /*
- * Calculate the PFNs for the buffer and ensure
- * they are with in addressable memory.
- */
- start_pfn = PHYS_PFN(tmp_addr);
- end_pfn = PHYS_PFN(tmp_addr + tmp_size - 1);
- if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn)) {
- pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n",
- tmp_addr, tmp_size);
- return -EINVAL;
- }
+ ret = ima_validate_range(tmp_addr, tmp_size);
+ if (ret)
+ return ret;
*addr = __va(tmp_addr);
*size = tmp_size;
_
Patches currently in -mm which might be from harshit.m.mogalapalli(a)oracle.com are
ima-add-ima_validate_range-for-previous-kernel-ima-buffer.patch
of-kexec-refactor-ima_get_kexec_buffer-to-use-ima_validate_range.patch
x86-kexec-add-a-sanity-check-on-previous-kernels-ima-kexec-buffer.patch
The patch titled
Subject: ima: add ima_validate_range() for previous kernel IMA buffer
has been added to the -mm mm-nonmm-unstable branch. Its filename is
ima-add-ima_validate_range-for-previous-kernel-ima-buffer.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Subject: ima: add ima_validate_range() for previous kernel IMA buffer
Date: Mon, 29 Dec 2025 00:15:21 -0800
Patch series "Address page fault in ima_restore_measurement_list()", v2.
When the second-stage kernel is booted via kexec with a limiting command
line such as "mem=<size>" we observe a pafe fault that happens.
BUG: unable to handle page fault for address: ffff97793ff47000
RIP: ima_restore_measurement_list+0xdc/0x45a
#PF: error_code(0x0000) not-present page
This happens on x86_64 only, as this is already fixed in aarch64 in
commit: cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer
against memory bounds")
This patch (of 3):
When the second-stage kernel is booted with a limiting command line (e.g.
"mem=<size>"), the IMA measurement buffer handed over from the previous
kernel may fall outside the addressable RAM of the new kernel. Accessing
such a buffer can fault during early restore.
Introduce a small generic helper, ima_validate_range(), which verifies
that a physical [start, end] range for the previous-kernel IMA buffer lies
within addressable memory:
- On x86, use pfn_range_is_mapped().
- On OF based architectures, use page_is_ram().
Link: https://lkml.kernel.org/r/20251229081523.622515-1-harshit.m.mogalapalli@ora…
Link: https://lkml.kernel.org/r/20251229081523.622515-2-harshit.m.mogalapalli@ora…
Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Ard Biesheuvel <ardb(a)kernel.org>
Cc: Borislav Betkov <bp(a)alien8.de>
Cc: guoweikang <guoweikang.kernel(a)gmail.com>
Cc: Henry Willard <henry.willard(a)oracle.com>
Cc: "H. Peter Anvin" <hpa(a)zytor.com>
Cc: Ingo Molnar <mingo(a)redhat.com>
Cc: Jiri Bohac <jbohac(a)suse.cz>
Cc: Joel Granados <joel.granados(a)kernel.org>
Cc: Jonathan McDowell <noodles(a)fb.com>
Cc: Mike Rapoport <rppt(a)kernel.org>
Cc: Mimi Zohar <zohar(a)linux.ibm.com>
Cc: Paul Webb <paul.x.webb(a)oracle.com>
Cc: Sohil Mehta <sohil.mehta(a)intel.com>
Cc: Sourabh Jain <sourabhjain(a)linux.ibm.com>
Cc: Thomas Gleinxer <tglx(a)linutronix.de>
Cc: Yifei Liu <yifei.l.liu(a)oracle.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
include/linux/ima.h | 1
security/integrity/ima/ima_kexec.c | 35 +++++++++++++++++++++++++++
2 files changed, 36 insertions(+)
--- a/include/linux/ima.h~ima-add-ima_validate_range-for-previous-kernel-ima-buffer
+++ a/include/linux/ima.h
@@ -69,6 +69,7 @@ static inline int ima_measure_critical_d
#ifdef CONFIG_HAVE_IMA_KEXEC
int __init ima_free_kexec_buffer(void);
int __init ima_get_kexec_buffer(void **addr, size_t *size);
+int ima_validate_range(phys_addr_t phys, size_t size);
#endif
#ifdef CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
--- a/security/integrity/ima/ima_kexec.c~ima-add-ima_validate_range-for-previous-kernel-ima-buffer
+++ a/security/integrity/ima/ima_kexec.c
@@ -12,6 +12,8 @@
#include <linux/kexec.h>
#include <linux/of.h>
#include <linux/ima.h>
+#include <linux/mm.h>
+#include <linux/overflow.h>
#include <linux/reboot.h>
#include <asm/page.h>
#include "ima.h"
@@ -294,3 +296,36 @@ void __init ima_load_kexec_buffer(void)
pr_debug("Error restoring the measurement list: %d\n", rc);
}
}
+
+/*
+ * ima_validate_range - verify a physical buffer lies in addressable RAM
+ * @phys: physical start address of the buffer from previous kernel
+ * @size: size of the buffer
+ *
+ * On success return 0. On failure returns -EINVAL so callers can skip
+ * restoring.
+ */
+int ima_validate_range(phys_addr_t phys, size_t size)
+{
+ unsigned long start_pfn, end_pfn;
+ phys_addr_t end_phys;
+
+ if (check_add_overflow(phys, (phys_addr_t)size - 1, &end_phys))
+ return -EINVAL;
+
+ start_pfn = PHYS_PFN(phys);
+ end_pfn = PHYS_PFN(end_phys);
+
+#ifdef CONFIG_X86
+ if (!pfn_range_is_mapped(start_pfn, end_pfn))
+#else
+ if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn))
+#endif
+ {
+ pr_warn("IMA: previous kernel measurement buffer %pa (size 0x%zx) lies outside available memory\n",
+ &phys, size);
+ return -EINVAL;
+ }
+
+ return 0;
+}
_
Patches currently in -mm which might be from harshit.m.mogalapalli(a)oracle.com are
ima-add-ima_validate_range-for-previous-kernel-ima-buffer.patch
of-kexec-refactor-ima_get_kexec_buffer-to-use-ima_validate_range.patch
x86-kexec-add-a-sanity-check-on-previous-kernels-ima-kexec-buffer.patch
The quilt patch titled
Subject: x86/kexec: add a sanity check on previous kernel's ima kexec buffer
has been removed from the -mm tree. Its filename was
x86-kexec-add-a-sanity-check-on-previous-kernels-ima-kexec-buffer.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Subject: x86/kexec: add a sanity check on previous kernel's ima kexec buffer
Date: Wed, 12 Nov 2025 11:30:02 -0800
When the second-stage kernel is booted via kexec with a limiting command
line such as "mem=<size>", the physical range that contains the carried
over IMA measurement list may fall outside the truncated RAM leading to a
kernel panic.
BUG: unable to handle page fault for address: ffff97793ff47000
RIP: ima_restore_measurement_list+0xdc/0x45a
#PF: error_code(0x0000) ��� not-present page
Other architectures already validate the range with page_is_ram(), as done
in commit: cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer
against memory bounds") do a similar check on x86.
[akpm(a)linux-foundation.org: fix comment typo]
Link: https://lkml.kernel.org/r/20251112193005.3772542-1-harshit.m.mogalapalli@or…
Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com>
Reported-by: Paul Webb <paul.x.webb(a)oracle.com>
Reviewed-by: Jonathan McDowell <noodles(a)meta.com>
Tested-by: Mimi Zohar <zohar(a)linux.ibm.com>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Ard Biesheuvel <ardb(a)kernel.org>
Cc: Borislav Betkov <bp(a)alien8.de>
Cc: guoweikang <guoweikang.kernel(a)gmail.com>
Cc: Henry Willard <henry.willard(a)oracle.com>
Cc: "H. Peter Anvin" <hpa(a)zytor.com>
Cc: Ingo Molnar <mingo(a)redhat.com>
Cc: Jiri Bohac <jbohac(a)suse.cz>
Cc: Joel Granados <joel.granados(a)kernel.org>
Cc: Mike Rapoport <rppt(a)kernel.org>
Cc: Sohil Mehta <sohil.mehta(a)intel.com>
Cc: Sourabh Jain <sourabhjain(a)linux.ibm.com>
Cc: Thomas Gleinxer <tglx(a)linutronix.de>
Cc: Yifei Liu <yifei.l.liu(a)oracle.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
arch/x86/kernel/setup.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
--- a/arch/x86/kernel/setup.c~x86-kexec-add-a-sanity-check-on-previous-kernels-ima-kexec-buffer
+++ a/arch/x86/kernel/setup.c
@@ -439,9 +439,23 @@ int __init ima_free_kexec_buffer(void)
int __init ima_get_kexec_buffer(void **addr, size_t *size)
{
+ unsigned long start_pfn, end_pfn;
+
if (!ima_kexec_buffer_size)
return -ENOENT;
+ /*
+ * Calculate the PFNs for the buffer and ensure
+ * they are within addressable memory.
+ */
+ start_pfn = PFN_DOWN(ima_kexec_buffer_phys);
+ end_pfn = PFN_DOWN(ima_kexec_buffer_phys + ima_kexec_buffer_size - 1);
+ if (!pfn_range_is_mapped(start_pfn, end_pfn)) {
+ pr_warn("IMA buffer at 0x%llx, size = 0x%zx beyond memory\n",
+ ima_kexec_buffer_phys, ima_kexec_buffer_size);
+ return -EINVAL;
+ }
+
*addr = __va(ima_kexec_buffer_phys);
*size = ima_kexec_buffer_size;
_
Patches currently in -mm which might be from harshit.m.mogalapalli(a)oracle.com are
The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 68d05693f8c031257a0822464366e1c2a239a512
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122953-federal-handclasp-1d09@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 68d05693f8c031257a0822464366e1c2a239a512 Mon Sep 17 00:00:00 2001
From: Chao Yu <chao(a)kernel.org>
Date: Wed, 5 Nov 2025 14:50:23 +0800
Subject: [PATCH] f2fs: fix to detect recoverable inode during dryrun of
find_fsync_dnodes()
mkfs.f2fs -f /dev/vdd
mount /dev/vdd /mnt/f2fs
touch /mnt/f2fs/foo
sync # avoid CP_UMOUNT_FLAG in last f2fs_checkpoint.ckpt_flags
touch /mnt/f2fs/bar
f2fs_io fsync /mnt/f2fs/bar
f2fs_io shutdown 2 /mnt/f2fs
umount /mnt/f2fs
blockdev --setro /dev/vdd
mount /dev/vdd /mnt/f2fs
mount: /mnt/f2fs: WARNING: source write-protected, mounted read-only.
For the case if we create and fsync a new inode before sudden power-cut,
without norecovery or disable_roll_forward mount option, the following
mount will succeed w/o recovering last fsynced inode.
The problem here is that we only check inode_list list after
find_fsync_dnodes() in f2fs_recover_fsync_data() to find out whether
there is recoverable data in the iamge, but there is a missed case, if
last fsynced inode is not existing in last checkpoint, then, we will
fail to get its inode due to nat of inode node is not existing in last
checkpoint, so the inode won't be linked in inode_list.
Let's detect such case in dyrun mode to fix this issue.
After this change, mount will fail as expected below:
mount: /mnt/f2fs: cannot mount /dev/vdd read-only.
dmesg(1) may have more information after failed mount system call.
demsg:
F2FS-fs (vdd): Need to recover fsync data, but write access unavailable, please try mount w/ disable_roll_forward or norecovery
Cc: stable(a)kernel.org
Fixes: 6781eabba1bd ("f2fs: give -EINVAL for norecovery and rw mount")
Signed-off-by: Chao Yu <chao(a)kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk(a)kernel.org>
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index 215e442db72c..d7faebaa3c6b 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -399,7 +399,7 @@ static int sanity_check_node_chain(struct f2fs_sb_info *sbi, block_t blkaddr,
}
static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
- bool check_only)
+ bool check_only, bool *new_inode)
{
struct curseg_info *curseg;
block_t blkaddr, blkaddr_fast;
@@ -447,16 +447,19 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
quota_inode = true;
}
- /*
- * CP | dnode(F) | inode(DF)
- * For this case, we should not give up now.
- */
entry = add_fsync_inode(sbi, head, ino_of_node(folio),
quota_inode);
if (IS_ERR(entry)) {
err = PTR_ERR(entry);
- if (err == -ENOENT)
+ /*
+ * CP | dnode(F) | inode(DF)
+ * For this case, we should not give up now.
+ */
+ if (err == -ENOENT) {
+ if (check_only)
+ *new_inode = true;
goto next;
+ }
f2fs_folio_put(folio, true);
break;
}
@@ -875,6 +878,7 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
int ret = 0;
unsigned long s_flags = sbi->sb->s_flags;
bool need_writecp = false;
+ bool new_inode = false;
f2fs_notice(sbi, "f2fs_recover_fsync_data: recovery fsync data, "
"check_only: %d", check_only);
@@ -890,8 +894,8 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
f2fs_down_write(&sbi->cp_global_sem);
/* step #1: find fsynced inode numbers */
- err = find_fsync_dnodes(sbi, &inode_list, check_only);
- if (err || list_empty(&inode_list))
+ err = find_fsync_dnodes(sbi, &inode_list, check_only, &new_inode);
+ if (err < 0 || (list_empty(&inode_list) && (!check_only || !new_inode)))
goto skip;
if (check_only) {
The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 68d05693f8c031257a0822464366e1c2a239a512
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122953-length-breeding-7553@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 68d05693f8c031257a0822464366e1c2a239a512 Mon Sep 17 00:00:00 2001
From: Chao Yu <chao(a)kernel.org>
Date: Wed, 5 Nov 2025 14:50:23 +0800
Subject: [PATCH] f2fs: fix to detect recoverable inode during dryrun of
find_fsync_dnodes()
mkfs.f2fs -f /dev/vdd
mount /dev/vdd /mnt/f2fs
touch /mnt/f2fs/foo
sync # avoid CP_UMOUNT_FLAG in last f2fs_checkpoint.ckpt_flags
touch /mnt/f2fs/bar
f2fs_io fsync /mnt/f2fs/bar
f2fs_io shutdown 2 /mnt/f2fs
umount /mnt/f2fs
blockdev --setro /dev/vdd
mount /dev/vdd /mnt/f2fs
mount: /mnt/f2fs: WARNING: source write-protected, mounted read-only.
For the case if we create and fsync a new inode before sudden power-cut,
without norecovery or disable_roll_forward mount option, the following
mount will succeed w/o recovering last fsynced inode.
The problem here is that we only check inode_list list after
find_fsync_dnodes() in f2fs_recover_fsync_data() to find out whether
there is recoverable data in the iamge, but there is a missed case, if
last fsynced inode is not existing in last checkpoint, then, we will
fail to get its inode due to nat of inode node is not existing in last
checkpoint, so the inode won't be linked in inode_list.
Let's detect such case in dyrun mode to fix this issue.
After this change, mount will fail as expected below:
mount: /mnt/f2fs: cannot mount /dev/vdd read-only.
dmesg(1) may have more information after failed mount system call.
demsg:
F2FS-fs (vdd): Need to recover fsync data, but write access unavailable, please try mount w/ disable_roll_forward or norecovery
Cc: stable(a)kernel.org
Fixes: 6781eabba1bd ("f2fs: give -EINVAL for norecovery and rw mount")
Signed-off-by: Chao Yu <chao(a)kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk(a)kernel.org>
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index 215e442db72c..d7faebaa3c6b 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -399,7 +399,7 @@ static int sanity_check_node_chain(struct f2fs_sb_info *sbi, block_t blkaddr,
}
static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
- bool check_only)
+ bool check_only, bool *new_inode)
{
struct curseg_info *curseg;
block_t blkaddr, blkaddr_fast;
@@ -447,16 +447,19 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
quota_inode = true;
}
- /*
- * CP | dnode(F) | inode(DF)
- * For this case, we should not give up now.
- */
entry = add_fsync_inode(sbi, head, ino_of_node(folio),
quota_inode);
if (IS_ERR(entry)) {
err = PTR_ERR(entry);
- if (err == -ENOENT)
+ /*
+ * CP | dnode(F) | inode(DF)
+ * For this case, we should not give up now.
+ */
+ if (err == -ENOENT) {
+ if (check_only)
+ *new_inode = true;
goto next;
+ }
f2fs_folio_put(folio, true);
break;
}
@@ -875,6 +878,7 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
int ret = 0;
unsigned long s_flags = sbi->sb->s_flags;
bool need_writecp = false;
+ bool new_inode = false;
f2fs_notice(sbi, "f2fs_recover_fsync_data: recovery fsync data, "
"check_only: %d", check_only);
@@ -890,8 +894,8 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
f2fs_down_write(&sbi->cp_global_sem);
/* step #1: find fsynced inode numbers */
- err = find_fsync_dnodes(sbi, &inode_list, check_only);
- if (err || list_empty(&inode_list))
+ err = find_fsync_dnodes(sbi, &inode_list, check_only, &new_inode);
+ if (err < 0 || (list_empty(&inode_list) && (!check_only || !new_inode)))
goto skip;
if (check_only) {