Re: + mm-vmalloc-fix-vbq-free-breakage.patch added to mm-hotfixes-unstable branch

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On Fri, May 31, 2024 at 4:12 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
>
> The patch titled
>      Subject: mm/vmalloc: fix vbq->free breakage
> has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
>      mm-vmalloc-fix-vbq-free-breakage.patch
>
> This patch will shortly appear at
>      https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmalloc-fix-vbq-free-breakage.patch
>
> This patch will later appear in the mm-hotfixes-unstable branch at
>     git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
>
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
>
> The -mm tree is included into linux-next via the mm-everything
> branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> and is updated there every 2-3 working days
>
> ------------------------------------------------------
> From: "hailong.liu" <hailong.liu@xxxxxxxx>
> Subject: mm/vmalloc: fix vbq->free breakage
> Date: Thu, 30 May 2024 17:31:08 +0800
>
> The function xa_for_each() in _vm_unmap_aliases() loops through all vbs.
> However, since commit 062eacf57ad9 ("mm: vmalloc: remove a global
> vmap_blocks xarray") the vb from xarray may not be on the corresponding
> CPU vmap_block_queue.  Consequently, purge_fragmented_block() might use
> the wrong vbq->lock to protect the free list, leading to vbq->free
> breakage.
>
> Link: https://lkml.kernel.org/r/20240530093108.4512-1-hailong.liu@xxxxxxxx
> Fixes: fc1e0d980037 ("mm/vmalloc: prevent stale TLBs in fully utilized blocks")
> Signed-off-by: Hailong.Liu <liuhailong@xxxxxxxx>
> Reported-by: Guangye Yang <guangye.yang@xxxxxxxxxxxx>
> Cc: Barry Song <21cnbao@xxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Cc: Gao Xiang <xiang@xxxxxxxxxx>
> Cc: Guangye Yang <guangye.yang@xxxxxxxxxxxx>
> Cc: liuhailong <liuhailong@xxxxxxxx>
> Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
> Cc: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> Cc: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
>  mm/vmalloc.c |    3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> --- a/mm/vmalloc.c~mm-vmalloc-fix-vbq-free-breakage
> +++ a/mm/vmalloc.c
> @@ -2830,10 +2830,9 @@ static void _vm_unmap_aliases(unsigned l
>         for_each_possible_cpu(cpu) {
>                 struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
>                 struct vmap_block *vb;
> -               unsigned long idx;
>
>                 rcu_read_lock();
> -               xa_for_each(&vbq->vmap_blocks, idx, vb) {
> +               list_for_each_entry_rcu(vb, &vbq->free, free_list) {
No, this is wrong as the fully used vb's TLB will be kept since they
are not on the vbq->free. I have sent Patchv2 out.
>                         spin_lock(&vb->lock);
>
>                         /*
> _
>
> Patches currently in -mm which might be from hailong.liu@xxxxxxxx are
>
> mm-vmalloc-fix-vbq-free-breakage.patch
>
>





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