From: "Mike Rapoport (Microsoft)" rppt@kernel.org
[ Upstream commit 469661d0d3a55a7ba1e7cb847c26baf78cace086 ]
Patch series "kho: add support for preserving vmalloc allocations", v5.
Following the discussion about preservation of memfd with LUO [1] these patches add support for preserving vmalloc allocations.
Any KHO uses case presumes that there's a data structure that lists physical addresses of preserved folios (and potentially some additional metadata). Allowing vmalloc preservations with KHO allows scalable preservation of such data structures.
For instance, instead of allocating array describing preserved folios in the fdt, memfd preservation can use vmalloc:
preserved_folios = vmalloc_array(nr_folios, sizeof(*preserved_folios)); memfd_luo_preserve_folios(preserved_folios, folios, nr_folios); kho_preserve_vmalloc(preserved_folios, &folios_info);
This patch (of 4):
Instead of checking if kho is finalized in each caller of __kho_preserve_order(), do it in the core function itself.
Link: https://lkml.kernel.org/r/20250921054458.4043761-1-rppt@kernel.org Link: https://lkml.kernel.org/r/20250921054458.4043761-2-rppt@kernel.org Link: https://lore.kernel.org/all/20250807014442.3829950-30-pasha.tatashin@soleen.... [1] Signed-off-by: Mike Rapoport (Microsoft) rppt@kernel.org Reviewed-by: Pratyush Yadav pratyush@kernel.org Cc: Alexander Graf graf@amazon.com Cc: Baoquan He bhe@redhat.com Cc: Changyuan Lyu changyuanl@google.com Cc: Chris Li chrisl@kernel.org Cc: Jason Gunthorpe jgg@nvidia.com Cc: Pasha Tatashin pasha.tatashin@soleen.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Stable-dep-of: fa759cd75bce ("kho: allocate metadata directly from the buddy allocator") Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/kexec_handover.c | 55 +++++++++++++++++++---------------------- 1 file changed, 26 insertions(+), 29 deletions(-)
diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index c58afd23a241f..4e5774a6f0738 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -91,6 +91,29 @@ struct kho_serialization { struct khoser_mem_chunk *preserved_mem_map; };
+struct kho_out { + struct blocking_notifier_head chain_head; + + struct dentry *dir; + + struct mutex lock; /* protects KHO FDT finalization */ + + struct kho_serialization ser; + bool finalized; +}; + +static struct kho_out kho_out = { + .chain_head = BLOCKING_NOTIFIER_INIT(kho_out.chain_head), + .lock = __MUTEX_INITIALIZER(kho_out.lock), + .ser = { + .fdt_list = LIST_HEAD_INIT(kho_out.ser.fdt_list), + .track = { + .orders = XARRAY_INIT(kho_out.ser.track.orders, 0), + }, + }, + .finalized = false, +}; + static void *xa_load_or_alloc(struct xarray *xa, unsigned long index, size_t sz) { void *elm, *res; @@ -149,6 +172,9 @@ static int __kho_preserve_order(struct kho_mem_track *track, unsigned long pfn,
might_sleep();
+ if (kho_out.finalized) + return -EBUSY; + physxa = xa_load(&track->orders, order); if (!physxa) { int err; @@ -631,29 +657,6 @@ int kho_add_subtree(struct kho_serialization *ser, const char *name, void *fdt) } EXPORT_SYMBOL_GPL(kho_add_subtree);
-struct kho_out { - struct blocking_notifier_head chain_head; - - struct dentry *dir; - - struct mutex lock; /* protects KHO FDT finalization */ - - struct kho_serialization ser; - bool finalized; -}; - -static struct kho_out kho_out = { - .chain_head = BLOCKING_NOTIFIER_INIT(kho_out.chain_head), - .lock = __MUTEX_INITIALIZER(kho_out.lock), - .ser = { - .fdt_list = LIST_HEAD_INIT(kho_out.ser.fdt_list), - .track = { - .orders = XARRAY_INIT(kho_out.ser.track.orders, 0), - }, - }, - .finalized = false, -}; - int register_kho_notifier(struct notifier_block *nb) { return blocking_notifier_chain_register(&kho_out.chain_head, nb); @@ -681,9 +684,6 @@ int kho_preserve_folio(struct folio *folio) const unsigned int order = folio_order(folio); struct kho_mem_track *track = &kho_out.ser.track;
- if (kho_out.finalized) - return -EBUSY; - return __kho_preserve_order(track, pfn, order); } EXPORT_SYMBOL_GPL(kho_preserve_folio); @@ -707,9 +707,6 @@ int kho_preserve_phys(phys_addr_t phys, size_t size) int err = 0; struct kho_mem_track *track = &kho_out.ser.track;
- if (kho_out.finalized) - return -EBUSY; - if (!PAGE_ALIGNED(phys) || !PAGE_ALIGNED(size)) return -EINVAL;