The patch titled Subject: mm/vmalloc: fix vmalloc which may return null if called with __GFP_NOFAIL has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-vmalloc-fix-vmalloc-which-may-return-null-if-called-with-__gfp_nofail.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: "Hailong.Liu" hailong.liu@oppo.com Subject: mm/vmalloc: fix vmalloc which may return null if called with __GFP_NOFAIL Date: Fri, 10 May 2024 18:01:31 +0800

commit a421ef303008 ("mm: allow !GFP_KERNEL allocations for kvmalloc") includes support for __GFP_NOFAIL, but it presents a conflict with commit dd544141b9eb ("vmalloc: back off when the current task is OOM-killed"). A possible scenario is as follows:

process-a __vmalloc_node_range(GFP_KERNEL | __GFP_NOFAIL) __vmalloc_area_node() vm_area_alloc_pages() --> oom-killer send SIGKILL to process-a if (fatal_signal_pending(current)) break; --> return NULL;

To fix this, do not check fatal_signal_pending() in vm_area_alloc_pages() if __GFP_NOFAIL set.

This issue occurred during OPLUS KASAN TEST. Below is part of the log -> oom-killer sends signal to process [65731.222840] [ T1308] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/apps/uid_10198,task=gs.intelligence,pid=32454,uid=10198

[65731.259685] [T32454] Call trace: [65731.259698] [T32454] dump_backtrace+0xf4/0x118 [65731.259734] [T32454] show_stack+0x18/0x24 [65731.259756] [T32454] dump_stack_lvl+0x60/0x7c [65731.259781] [T32454] dump_stack+0x18/0x38 [65731.259800] [T32454] mrdump_common_die+0x250/0x39c [mrdump] [65731.259936] [T32454] ipanic_die+0x20/0x34 [mrdump] [65731.260019] [T32454] atomic_notifier_call_chain+0xb4/0xfc [65731.260047] [T32454] notify_die+0x114/0x198 [65731.260073] [T32454] die+0xf4/0x5b4 [65731.260098] [T32454] die_kernel_fault+0x80/0x98 [65731.260124] [T32454] __do_kernel_fault+0x160/0x2a8 [65731.260146] [T32454] do_bad_area+0x68/0x148 [65731.260174] [T32454] do_mem_abort+0x151c/0x1b34 [65731.260204] [T32454] el1_abort+0x3c/0x5c [65731.260227] [T32454] el1h_64_sync_handler+0x54/0x90 [65731.260248] [T32454] el1h_64_sync+0x68/0x6c

[65731.260269] [T32454] z_erofs_decompress_queue+0x7f0/0x2258 --> be->decompressed_pages = kvcalloc(be->nr_pages, sizeof(struct page *), GFP_KERNEL | __GFP_NOFAIL); kernel panic by NULL pointer dereference. erofs assume kvmalloc with __GFP_NOFAIL never return NULL. [65731.260293] [T32454] z_erofs_runqueue+0xf30/0x104c [65731.260314] [T32454] z_erofs_readahead+0x4f0/0x968 [65731.260339] [T32454] read_pages+0x170/0xadc [65731.260364] [T32454] page_cache_ra_unbounded+0x874/0xf30 [65731.260388] [T32454] page_cache_ra_order+0x24c/0x714 [65731.260411] [T32454] filemap_fault+0xbf0/0x1a74 [65731.260437] [T32454] __do_fault+0xd0/0x33c [65731.260462] [T32454] handle_mm_fault+0xf74/0x3fe0 [65731.260486] [T32454] do_mem_abort+0x54c/0x1b34 [65731.260509] [T32454] el0_da+0x44/0x94 [65731.260531] [T32454] el0t_64_sync_handler+0x98/0xb4 [65731.260553] [T32454] el0t_64_sync+0x198/0x19c

Link: https://lkml.kernel.org/r/20240510100131.1865-1-hailong.liu@oppo.com Fixes: 9376130c390a ("mm/vmalloc: add support for __GFP_NOFAIL") Signed-off-by: Hailong.Liu hailong.liu@oppo.com Acked-by: Michal Hocko mhocko@suse.com Suggested-by: Barry Song 21cnbao@gmail.com Reported-by: Oven liyangouwen1@oppo.com Reviewed-by: Barry Song baohua@kernel.org Reviewed-by: Uladzislau Rezki (Sony) urezki@gmail.com Cc: Chao Yu chao@kernel.org Cc: Christoph Hellwig hch@infradead.org Cc: Gao Xiang xiang@kernel.org Cc: Lorenzo Stoakes lstoakes@gmail.com Cc: Michal Hocko mhocko@suse.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/vmalloc.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/mm/vmalloc.c~mm-vmalloc-fix-vmalloc-which-may-return-null-if-called-with-__gfp_nofail +++ a/mm/vmalloc.c @@ -3492,7 +3492,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid, { unsigned int nr_allocated = 0; gfp_t alloc_gfp = gfp; - bool nofail = false; + bool nofail = gfp & __GFP_NOFAIL; struct page *page; int i;

@@ -3549,12 +3549,11 @@ vm_area_alloc_pages(gfp_t gfp, int nid, * and compaction etc. */ alloc_gfp &= ~__GFP_NOFAIL; - nofail = true; }

/* High-order pages or fallback path if "bulk" fails. */ while (nr_allocated < nr_pages) { - if (fatal_signal_pending(current)) + if (!nofail && fatal_signal_pending(current)) break;

if (nid == NUMA_NO_NODE) _

Patches currently in -mm which might be from hailong.liu@oppo.com are

mm-vmalloc-fix-vmalloc-which-may-return-null-if-called-with-__gfp_nofail.patch