Messages in this thread Patch in this message | | | Date | Mon, 18 Dec 2023 11:34:59 +0800 | Subject | Re: [PATCH] mm: migrate: fix getting incorrect page mapping during page migration | From | Baolin Wang <> |
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On 12/15/2023 11:01 PM, Matthew Wilcox wrote: > On Fri, Dec 15, 2023 at 02:51:43PM +0000, Matthew Wilcox wrote: >> I'm not saying no to this fix, but dump_mapping() is supposed to be >> resilient against this. Is the issue that 'dentry' is NULL, or is it >> some field within dentry that is NULL? eg, would this fix your >> case? > > Uh, dentry is an on-stack dentry. So obviously it's a pointer within it > that's NULL. Maybe this, having stared at the implementation of %pd?
Yes, I think below check can avoid crash of dentry_name() used by '%pd'. Maybe we should also initialize on-stack dentry by struct dentry dentry = { };
I can send a patch with your suggestion. Thanks.
> +++ b/fs/inode.c > @@ -588,7 +588,8 @@ void dump_mapping(const struct address_space *mapping) > } > > dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias); > - if (get_kernel_nofault(dentry, dentry_ptr)) { > + if (get_kernel_nofault(dentry, dentry_ptr) || > + !dentry->d_parent || !dentry->d_name) { > pr_warn("aops:%ps ino:%lx invalid dentry:%px\n", > a_ops, ino, dentry_ptr); > return;
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