diff options
author | Roman Gushchin <guro@fb.com> | 2021-02-05 05:32:36 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-05 22:03:47 +0300 |
commit | 2dcb3964544177c51853a210b6ad400de78ef17d (patch) | |
tree | 2368ab5308b32a56feed751962b763062a2341c0 | |
parent | 1c2f67308af4c102b4e1e6cd6f69819ae59408e0 (diff) | |
download | linux-2dcb3964544177c51853a210b6ad400de78ef17d.tar.xz |
memblock: do not start bottom-up allocations with kernel_end
With kaslr the kernel image is placed at a random place, so starting the
bottom-up allocation with the kernel_end can result in an allocation
failure and a warning like this one:
hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node
------------[ cut here ]------------
memblock: bottom-up allocation failed, memory hotremove may be affected
WARNING: CPU: 0 PID: 0 at mm/memblock.c:332 memblock_find_in_range_node+0x178/0x25a
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.10.0+ #1169
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014
RIP: 0010:memblock_find_in_range_node+0x178/0x25a
Code: e9 6d ff ff ff 48 85 c0 0f 85 da 00 00 00 80 3d 9b 35 df 00 00 75 15 48 c7 c7 c0 75 59 88 c6 05 8b 35 df 00 01 e8 25 8a fa ff <0f> 0b 48 c7 44 24 20 ff ff ff ff 44 89 e6 44 89 ea 48 c7 c1 70 5c
RSP: 0000:ffffffff88803d18 EFLAGS: 00010086 ORIG_RAX: 0000000000000000
RAX: 0000000000000000 RBX: 0000000240000000 RCX: 00000000ffffdfff
RDX: 00000000ffffdfff RSI: 00000000ffffffea RDI: 0000000000000046
RBP: 0000000100000000 R08: ffffffff88922788 R09: 0000000000009ffb
R10: 00000000ffffe000 R11: 3fffffffffffffff R12: 0000000000000000
R13: 0000000000000000 R14: 0000000080000000 R15: 00000001fb42c000
FS: 0000000000000000(0000) GS:ffffffff88f71000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffa080fb401000 CR3: 00000001fa80a000 CR4: 00000000000406b0
Call Trace:
memblock_alloc_range_nid+0x8d/0x11e
cma_declare_contiguous_nid+0x2c4/0x38c
hugetlb_cma_reserve+0xdc/0x128
flush_tlb_one_kernel+0xc/0x20
native_set_fixmap+0x82/0xd0
flat_get_apic_id+0x5/0x10
register_lapic_address+0x8e/0x97
setup_arch+0x8a5/0xc3f
start_kernel+0x66/0x547
load_ucode_bsp+0x4c/0xcd
secondary_startup_64_no_verify+0xb0/0xbb
random: get_random_bytes called from __warn+0xab/0x110 with crng_init=0
---[ end trace f151227d0b39be70 ]---
At the same time, the kernel image is protected with memblock_reserve(),
so we can just start searching at PAGE_SIZE. In this case the bottom-up
allocation has the same chances to success as a top-down allocation, so
there is no reason to fallback in the case of a failure. All together it
simplifies the logic.
Link: https://lkml.kernel.org/r/20201217201214.3414100-2-guro@fb.com
Fixes: 8fabc623238e ("powerpc: Ensure that swiotlb buffer is allocated from low memory")
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Wonhyuk Yang <vvghjk1234@gmail.com>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | mm/memblock.c | 49 |
1 files changed, 6 insertions, 43 deletions
diff --git a/mm/memblock.c b/mm/memblock.c index 1eaaec1e7687..8d9b5f1e7040 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -275,14 +275,6 @@ __memblock_find_range_top_down(phys_addr_t start, phys_addr_t end, * * Find @size free area aligned to @align in the specified range and node. * - * When allocation direction is bottom-up, the @start should be greater - * than the end of the kernel image. Otherwise, it will be trimmed. The - * reason is that we want the bottom-up allocation just near the kernel - * image so it is highly likely that the allocated memory and the kernel - * will reside in the same node. - * - * If bottom-up allocation failed, will try to allocate memory top-down. - * * Return: * Found address on success, 0 on failure. */ @@ -291,8 +283,6 @@ static phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t size, phys_addr_t end, int nid, enum memblock_flags flags) { - phys_addr_t kernel_end, ret; - /* pump up @end */ if (end == MEMBLOCK_ALLOC_ACCESSIBLE || end == MEMBLOCK_ALLOC_KASAN) @@ -301,40 +291,13 @@ static phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t size, /* avoid allocating the first page */ start = max_t(phys_addr_t, start, PAGE_SIZE); end = max(start, end); - kernel_end = __pa_symbol(_end); - - /* - * try bottom-up allocation only when bottom-up mode - * is set and @end is above the kernel image. - */ - if (memblock_bottom_up() && end > kernel_end) { - phys_addr_t bottom_up_start; - - /* make sure we will allocate above the kernel */ - bottom_up_start = max(start, kernel_end); - /* ok, try bottom-up allocation first */ - ret = __memblock_find_range_bottom_up(bottom_up_start, end, - size, align, nid, flags); - if (ret) - return ret; - - /* - * we always limit bottom-up allocation above the kernel, - * but top-down allocation doesn't have the limit, so - * retrying top-down allocation may succeed when bottom-up - * allocation failed. - * - * bottom-up allocation is expected to be fail very rarely, - * so we use WARN_ONCE() here to see the stack trace if - * fail happens. - */ - WARN_ONCE(IS_ENABLED(CONFIG_MEMORY_HOTREMOVE), - "memblock: bottom-up allocation failed, memory hotremove may be affected\n"); - } - - return __memblock_find_range_top_down(start, end, size, align, nid, - flags); + if (memblock_bottom_up()) + return __memblock_find_range_bottom_up(start, end, size, align, + nid, flags); + else + return __memblock_find_range_top_down(start, end, size, align, + nid, flags); } /** |