The patch titled Subject: mm/vmalloc: add a safer version of find_vm_area() for debug has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.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: "Joel Fernandes (Google)" joel@joelfernandes.org Subject: mm/vmalloc: add a safer version of find_vm_area() for debug Date: Mon, 4 Sep 2023 18:08:04 +0000

It is unsafe to dump vmalloc area information when trying to do so from some contexts. Add a safer trylock version of the same function to do a best-effort VMA finding and use it from vmalloc_dump_obj().

[applied test robot feedback on unused function fix.] [applied Uladzislau feedback on locking.] Link: https://lkml.kernel.org/r/20230904180806.1002832-1-joel@joelfernandes.org Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory") Signed-off-by: Joel Fernandes (Google) joel@joelfernandes.org Reviewed-by: Uladzislau Rezki (Sony) urezki@gmail.com Reported-by: Zhen Lei thunder.leizhen@huaweicloud.com Cc: Paul E. McKenney paulmck@kernel.org Cc: Zqiang qiang.zhang1211@gmail.com Cc: stable@vger.kernel.org Cc: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/vmalloc.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-)

--- a/mm/vmalloc.c~mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug +++ a/mm/vmalloc.c @@ -4278,14 +4278,32 @@ void pcpu_free_vm_areas(struct vm_struct #ifdef CONFIG_PRINTK bool vmalloc_dump_obj(void *object) { - struct vm_struct *vm; void *objp = (void *)PAGE_ALIGN((unsigned long)object); + const void *caller; + struct vm_struct *vm; + struct vmap_area *va; + unsigned long addr; + unsigned int nr_pages; + + if (!spin_trylock(&vmap_area_lock)) + return false; + va = __find_vmap_area((unsigned long)objp, &vmap_area_root); + if (!va) { + spin_unlock(&vmap_area_lock); + return false; + }

- vm = find_vm_area(objp); - if (!vm) + vm = va->vm; + if (!vm) { + spin_unlock(&vmap_area_lock); return false; + } + addr = (unsigned long)vm->addr; + caller = vm->caller; + nr_pages = vm->nr_pages; + spin_unlock(&vmap_area_lock); pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n", - vm->nr_pages, (unsigned long)vm->addr, vm->caller); + nr_pages, addr, caller); return true; } #endif _

Patches currently in -mm which might be from joel@joelfernandes.org are

mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch