On 2024/11/9 04:09, Jann Horn wrote:
On Fri, Nov 8, 2024 at 8:38 AM Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
On 2024/11/8 06:39, Jann Horn wrote:
On Thu, Oct 31, 2024 at 9:14 AM Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
free_pte
pte_free_tlb
__pte_free_tlb
___pte_free_tlb
paravirt_tlb_remove_table
tlb_remove_table [!CONFIG_PARAVIRT, Xen PV, Hyper-V, KVM]
[no-free-memory slowpath:]
tlb_table_invalidate
tlb_remove_table_one
tlb_remove_table_sync_one [does IPI for GUP-fast]
^
It seems that this step can be ommitted when
CONFIG_PT_RECLAIM is enabled, because GUP-fast will
disable IRQ, which can also serve as the RCU critical
section.
Yeah, I think so too.
Will remove this step in the next version.
+#ifdef CONFIG_PT_RECLAIM
+static inline void __tlb_remove_table_one_rcu(struct rcu_head *head)
+{
+ struct page *page;
+
+ page = container_of(head, struct page, rcu_head);
+ free_page_and_swap_cache(page);
+}
Why free_page_and_swap_cache()? Page tables shouldn't have swap cache,
so I think something like put_page() would do the job.
Ah, I just did the same thing as __tlb_remove_table(). But I also
have the same doubt as you, why does __tlb_remove_table() need to
call free_page_and_swap_cache() instead of put_page().
I think commit 9e52fc2b50de3a1c08b44f94c610fbe998c0031a probably just
copy-pasted it from a more generic page freeing path...
I guess so. Will use put_page() instead of free_page_and_swap_cache()
in the next version. But for __tlb_remove_table(), I prefer to send
a separate patch to modify.
Thanks!
