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* [rpms/grub2] f44: mm: try allocating regions above defined limit as last resource
@ 2026-08-14 16:08 Leo Sandoval
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From: Leo Sandoval @ 2026-08-14 16:08 UTC (permalink / raw)
To: git-commits
A new commit has been pushed.
Repo : rpms/grub2
Branch : f44
Commit : 5cb61ad134463574b9e7528291e6c5331c6d3a6c
Author : Leo Sandoval <lsandova@redhat.com>
Date : 2026-08-13T13:29:20-06:00
Stats : +157/-1 in 3 file(s)
URL : https://src.fedoraproject.org/rpms/grub2/c/5cb61ad134463574b9e7528291e6c5331c6d3a6c?branch=f44
Log:
mm: try allocating regions above defined limit as last resource
As indicated on the patch, this new approach tries allocating regions
above defined limit with the hope of getting large regions so
allocations can fit but it may impact some systems where DMA is done
wrong on these regions.
Related: #2263643
Related: #2427945
Related: #2422881
Related: #2453022
Related: #2451630
Related: #2450672
Signed-off-by: Leo Sandoval <lsandova@redhat.com>
---
diff --git a/0424-mm-try-allocating-regions-above-defined-limit-as-las.patch b/0424-mm-try-allocating-regions-above-defined-limit-as-las.patch
new file mode 100644
index 0000000..2714077
--- /dev/null
+++ b/0424-mm-try-allocating-regions-above-defined-limit-as-las.patch
@@ -0,0 +1,146 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Leo Sandoval <lsandova@redhat.com>
+Date: Fri, 26 Jun 2026 15:14:37 -0600
+Subject: [PATCH] mm: try allocating regions above defined limit as last
+ resource
+
+This is yet another approach to overcome out-of-memory issues on those
+systems with constrained and fragmented EFI memories, where large files,
+e.g. initrd, which may cause out-of-memory errors stopping the boot process.
+
+This time, the approach is not to hardcode the
+maximum (GRUB_EFI_MAX_ALLOCATION_ADDRESS=2^64-1) but instead increase
+the filtering range to include EFI's conventional memory above
+GRUB_EFI_MAX_ALLOCATION_ADDRESS (2GB).
+
+Conceptually this is the same as increasing
+GRUB_EFI_MAX_ALLOCATION_ADDRESS to 2^64-1 but this time the memory
+allocator algorithm is a bit smarter: it first tries current
+allocation methods below GRUB_EFI_MAX_ALLOCATION_ADDRESS, not
+impacting current boots and if fails, it tries above this value.
+
+This is not a silver-buller for all firmware types: there may be some
+machines with constrained and fragmented memories besides with firmware
+drivers which cannot properly DMA above
+GRUB_EFI_MAX_ALLOCATION_ADDRESS, where although no OOM issues are
+seeing, boot can fail in other areas. On these particular systems,
+there is not much GRUB can do.
+
+Signed-off-by: Leo Sandoval <lsandova@redhat.com>
+---
+ grub-core/kern/efi/mm.c | 22 +++++++++++++---------
+ grub-core/kern/mm.c | 25 +++++++++++++++++++++++--
+ include/grub/mm.h | 1 +
+ 3 files changed, 37 insertions(+), 11 deletions(-)
+
+diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
+index 464fe1c3c..22a936a6e 100644
+--- a/grub-core/kern/efi/mm.c
++++ b/grub-core/kern/efi/mm.c
+@@ -470,10 +470,12 @@ static grub_efi_memory_descriptor_t *
+ filter_memory_map (grub_efi_memory_descriptor_t *memory_map,
+ grub_efi_memory_descriptor_t *filtered_memory_map,
+ grub_efi_uintn_t desc_size,
+- grub_efi_memory_descriptor_t *memory_map_end)
++ grub_efi_memory_descriptor_t *memory_map_end,
++ unsigned int flags)
+ {
+ grub_efi_memory_descriptor_t *desc;
+ grub_efi_memory_descriptor_t *filtered_desc;
++ unsigned int no_limit = flags & GRUB_MM_ADD_REGION_NO_LIMIT;
+
+ for (desc = memory_map, filtered_desc = filtered_memory_map;
+ desc < memory_map_end;
+@@ -481,7 +483,7 @@ filter_memory_map (grub_efi_memory_descriptor_t *memory_map,
+ {
+ if (desc->type == GRUB_EFI_CONVENTIONAL_MEMORY
+ #if 1
+- && desc->physical_start <= GRUB_EFI_MAX_ALLOCATION_ADDRESS
++ && (no_limit || desc->physical_start <= GRUB_EFI_MAX_ALLOCATION_ADDRESS)
+ #endif
+ && desc->physical_start + PAGES_TO_BYTES (desc->num_pages) > 0x100000
+ && desc->num_pages != 0)
+@@ -497,12 +499,13 @@ filter_memory_map (grub_efi_memory_descriptor_t *memory_map,
+ }
+
+ #if 1
+- if (BYTES_TO_PAGES (filtered_desc->physical_start)
+- + filtered_desc->num_pages
+- > BYTES_TO_PAGES_DOWN (GRUB_EFI_MAX_ALLOCATION_ADDRESS))
+- filtered_desc->num_pages
+- = (BYTES_TO_PAGES_DOWN (GRUB_EFI_MAX_ALLOCATION_ADDRESS)
+- - BYTES_TO_PAGES (filtered_desc->physical_start));
++ if (!no_limit)
++ if (BYTES_TO_PAGES (filtered_desc->physical_start)
++ + filtered_desc->num_pages
++ > BYTES_TO_PAGES_DOWN (GRUB_EFI_MAX_ALLOCATION_ADDRESS))
++ filtered_desc->num_pages
++ = (BYTES_TO_PAGES_DOWN (GRUB_EFI_MAX_ALLOCATION_ADDRESS)
++ - BYTES_TO_PAGES (filtered_desc->physical_start));
+ #endif
+
+ if (filtered_desc->num_pages == 0)
+@@ -729,7 +732,8 @@ grub_efi_mm_add_regions (grub_size_t required_bytes, unsigned int flags)
+ filtered_memory_map = memory_map_end;
+
+ filtered_memory_map_end = filter_memory_map (memory_map, filtered_memory_map,
+- desc_size, memory_map_end);
++ desc_size, memory_map_end,
++ flags);
+
+ /* Sort the filtered descriptors, so that GRUB can allocate pages
+ from smaller regions. */
+diff --git a/grub-core/kern/mm.c b/grub-core/kern/mm.c
+index 819bc5126..49d4b5284 100644
+--- a/grub-core/kern/mm.c
++++ b/grub-core/kern/mm.c
+@@ -536,14 +536,35 @@ grub_memalign (grub_size_t align, grub_size_t size)
+ goto again;
+ }
+
+- /* fallthrough */
+-
+ case 2:
+ /* Invalidate disk caches. */
+ grub_disk_cache_invalidate_all ();
+ count++;
+ goto again;
+
++
++#if defined (GRUB_MACHINE_EFI) && defined (__x86_64__)
++ case 3:
++ /* Request additional pages, anything at all, but this time
++ without the GRUB_EFI_MAX_ALLOCATION_ADDRESS limit.
++ This is a risky approach because some cannot DMA above 2GB,
++ but give it try and hope for the best.
++ */
++ count++;
++
++ if (grub_mm_add_region_fn != NULL)
++ {
++ /*
++ * Try again even if this fails, in case it was able to partially
++ * satisfy the request
++ */
++ grub_mm_add_region_fn (grow, GRUB_MM_ADD_REGION_NO_LIMIT);
++ goto again;
++ }
++#endif
++
++ /* fallthrough */
++
+ default:
+ break;
+ }
+diff --git a/include/grub/mm.h b/include/grub/mm.h
+index 8ee1fc717..d3bd3c057 100644
+--- a/include/grub/mm.h
++++ b/include/grub/mm.h
+@@ -32,6 +32,7 @@
+
+ #define GRUB_MM_ADD_REGION_NONE 0
+ #define GRUB_MM_ADD_REGION_CONSECUTIVE (1 << 0)
++#define GRUB_MM_ADD_REGION_NO_LIMIT (1 << 1)
+
+ /*
+ * Function used to request memory regions of `grub_size_t` bytes. The second
diff --git a/grub.patches b/grub.patches
index 40f9202..e08e775 100644
--- a/grub.patches
+++ b/grub.patches
@@ -420,3 +420,4 @@ Patch0420: 0420-util-grub-editenv-remove-stale-env_block-on-unsuppor.patch
Patch0421: 0421-grub-get-kernel-settings-Treate-kernel-uki-dtbloader.patch
Patch0422: 0422-mdraid-fix-metadata-1.0-detection-in-userspace-utils-on-IEEE1275.patch
Patch0423: 0423-grub-install-use-search.fs_uuid-for-RAID1-on-IEEE1275.patch
+Patch0424: 0424-mm-try-allocating-regions-above-defined-limit-as-las.patch
\ No newline at end of file
diff --git a/grub2.spec b/grub2.spec
index 5ae6715..d5a3790 100644
--- a/grub2.spec
+++ b/grub2.spec
@@ -17,7 +17,7 @@
Name: grub2
Epoch: 1
Version: 2.12
-Release: 63%{?dist}
+Release: 64%{?dist}
Summary: Bootloader with support for Linux, Multiboot and more
License: GPL-3.0-or-later
URL: http://www.gnu.org/software/grub/
@@ -611,6 +611,15 @@ fi
%endif
%changelog
+* Thu Aug 13 2026 Leo Sandoval <lsandova@redhat.com> - 2.12-64
+- mm: try allocating regions above defined limit as last resource
+- Related: #2263643
+- Related: #2427945
+- Related: #2422881
+- Related: #2453022
+- Related: #2451630
+- Related: #2450672
+
* Thu Jun 25 2026 Leo Sandoval <lsandova@redhat.com> - 2.12-63
- spec efi postttrans: remove mountpoint check
- Related: #2492140
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