On Tue, Mar 11, 2025 at 07:27:23AM +0200, Mike Rapoport wrote: >Hi Wei, > >On Mon, Mar 10, 2025 at 09:51:24AM +0000, Wei Yang wrote: >> On Sun, Feb 23, 2025 at 12:22:29AM +0000, Wei Yang wrote: >> >On Wed, Feb 19, 2025 at 09:24:31AM +0200, Mike Rapoport wrote: >> >>Hi, >> >> >> >>On Tue, Feb 18, 2025 at 03:50:04PM +0000, Wei Yang wrote: >> >>> On Thu, Feb 06, 2025 at 03:27:42PM +0200, Mike Rapoport wrote: >> >>> >From: "Mike Rapoport (Microsoft)" <[email protected]> >> >>> > >> >>> >to denote areas that were reserved for kernel use either directly with >> >>> >memblock_reserve_kern() or via memblock allocations. >> >>> > >> >>> >Signed-off-by: Mike Rapoport (Microsoft) <[email protected]> >> >>> >--- >> >>> > include/linux/memblock.h | 16 +++++++++++++++- >> >>> > mm/memblock.c | 32 ++++++++++++++++++++++++-------- >> >>> > 2 files changed, 39 insertions(+), 9 deletions(-) >> >>> > >> >>> >diff --git a/include/linux/memblock.h b/include/linux/memblock.h >> >>> >index e79eb6ac516f..65e274550f5d 100644 >> >>> >--- a/include/linux/memblock.h >> >>> >+++ b/include/linux/memblock.h >> >>> >@@ -50,6 +50,7 @@ enum memblock_flags { >> >>> > MEMBLOCK_NOMAP = 0x4, /* don't add to kernel direct >> >>> > mapping */ >> >>> > MEMBLOCK_DRIVER_MANAGED = 0x8, /* always detected via a driver >> >>> > */ >> >>> > MEMBLOCK_RSRV_NOINIT = 0x10, /* don't initialize struct >> >>> > pages */ >> >>> >+ MEMBLOCK_RSRV_KERN = 0x20, /* memory reserved for kernel >> >>> >use */ >> >>> >> >>> Above memblock_flags, there are comments on explaining those flags. >> >>> >> >>> Seems we miss it for MEMBLOCK_RSRV_KERN. >> >> >> >>Right, thanks! >> >> >> >>> > >> >>> > #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP >> >>> >@@ -1459,14 +1460,14 @@ phys_addr_t __init >> >>> >memblock_alloc_range_nid(phys_addr_t size, >> >>> > again: >> >>> > found = memblock_find_in_range_node(size, align, start, end, >> >>> > nid, >> >>> > flags); >> >>> >- if (found && !memblock_reserve(found, size)) >> >>> >+ if (found && !__memblock_reserve(found, size, nid, >> >>> >MEMBLOCK_RSRV_KERN)) >> >>> >> >>> Maybe we could use memblock_reserve_kern() directly. If my understanding >> >>> is >> >>> correct, the reserved region's nid is not used. >> >> >> >>We use nid of reserved regions in reserve_bootmem_region() (commit >> >>61167ad5fecd ("mm: pass nid to reserve_bootmem_region()")) but KHO needs to >> >>know the distribution of reserved memory among the nodes before >> >>memmap_init_reserved_pages(). >> >> >> > >> >I took another look into this commit. There maybe a very corner case in >> >which >> >will leave a reserved region with no nid set. >> > >> >memmap_init_reserved_pages() >> > for_each_mem_region() { >> > ... >> > memblock_set_node(start, end, &memblock.reserved, nid); >> > } >> > >> >We leverage the iteration here to set nid to all regions in >> >memblock.reserved. >> >But memblock_set_node() may call memblock_double_array() to expand the >> >array, >> >which may get a range before current start. So we would miss to set the >> >correct nid to the new reserved region. >> > >> >I have tried to create a case in memblock test. This would happen when there >> >are 126 memblock.reserved regions. And the last region is across the last >> >two >> >node. >> > >> >One way to fix this is compare type->max in memblock_set_node(). Then check >> >this return value in memmap_init_reserved_pages(). If we found the size >> >changes, repeat the iteration. >> > >> >But this is a very trivial one, not sure it worth fix. >> > >> >> Hi, Mike >> >> I have done a user space test which shows we may have a chance to leave a >> region with non-nid set. >> >> Not sure you are ok with my approach of fixing. > >Wouldn't it be better to check for a change in reserved.max in >memmap_init_reserved_pages()? >
Sounds better. Previously I thought we need to hide detail from user, but actually it is already in memblock.c :-) If you agree, I would like to prepare a fix. >> -- >> Wei Yang >> Help you, Help me > >-- >Sincerely yours, >Mike. -- Wei Yang Help you, Help me
