linux-kernel - Re: [PATCH 2/2] uprobe: collapse THP pmd after removing all uprobes

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Message-ID: <20190731161614.GC25078@redhat.com>
Date:   Wed, 31 Jul 2019 18:16:14 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Song Liu <songliubraving@...com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, matthew.wilcox@...cle.com,
        kirill.shutemov@...ux.intel.com, kernel-team@...com,
        william.kucharski@...cle.com, srikar@...ux.vnet.ibm.com
Subject: Re: [PATCH 2/2] uprobe: collapse THP pmd after removing all uprobes

On 07/28, Song Liu wrote:
>
> @@ -525,6 +527,9 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
>  
>  				/* dec_mm_counter for old_page */
>  				dec_mm_counter(mm, MM_ANONPAGES);
> +
> +				if (PageCompound(orig_page))
> +					orig_page_huge = true;

I am wondering how find_get_page() can return a PageCompound() page...

IIUC, this is only possible if shmem_file(), right?

Oleg.