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Thu, 30 May 2024 03:54:53 -0400 X-MC-Unique: xrdTrkz6O8W-ukOJNc3WmA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 43BEC3806700; Thu, 30 May 2024 07:54:52 +0000 (UTC) Received: from localhost (unknown [10.72.116.34]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1DCA9400EAC; Thu, 30 May 2024 07:54:50 +0000 (UTC) Date: Thu, 30 May 2024 15:54:47 +0800 From: Baoquan He To: Zhaoyang Huang Cc: "zhaoyang.huang" , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, steve.kang@unisoc.com, Thomas Gleixner Subject: Re: [PATCH] mm: fix incorrect vbq reference in purge_fragmented_block Message-ID: References: <20240530025144.1570865-1-zhaoyang.huang@unisoc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 X-Rspam-User: X-Stat-Signature: 9r91jegz6xpgrbepiuzkeppub3hafu5p X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: A39B680004 X-HE-Tag: 1717055697-895458 X-HE-Meta: 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 eTCMVMeV aBAyDnicUNFfKbuiQjIdMP9DA5LU8aJk/JjHNCUvNpdgTff88TNJockd8pQRgQ96BtHtUIDDmWGAmkJBP2/XJiHUAfnaD/P3hq6Gem8L15/flzk1yXiuCqUAQ+06/K4XqO2c+xOOdP+ESklbQBn+SmsxMl9qNGHQakwxuya48BvRRRVu8CQdrOsHlNbanxI+9GM5Q2otTpkSGEZjFDmFADcDPRlNCcoBPdpxPvzWk2ab9D7DM34CxaNLgU7yolZr1Gm3QAc1mayYta/XZ3T4kynRstvyEu7GU8L2ZbAG1hzzb6Uxv3Uq/TLL3DRHIuijKEh+XIr9HYcJti8gJva4U0odeqtGy9LWMccUI X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/30/24 at 03:35pm, Zhaoyang Huang wrote: > On Thu, May 30, 2024 at 3:19 PM Baoquan He wrote: > > > > On 05/30/24 at 10:51am, zhaoyang.huang wrote: > > > From: Zhaoyang Huang > > > > > > Broken vbq->free reported on a v6.6 based system which is caused > > > by invalid vbq->lock protect over vbq->free in purge_fragmented_block. > > > This should be introduced by the Fixes below which ignored vbq->lock > > > matter. > > > > It will be helpful to provide more details, what's the symptom of the > > brekage, and in which case vbq->free is broken. > Vmalloc area runs out in our ARM64 system during an erofs test as > vm_map_ram failed[1]. We find that one vbq->free->next point to > vbq->free which makes list_for_each_entry_rcu can not iterate the list > and find the BUG. Thanks for these information which are very helpful and important. They need be put in log for easier understanding. I am wondering about the vbq->free list breakage by the run out vmalloc area, could you say more about how it's caused? And do you think we need fix that vbq->free list breakage either? > > [1] > PID: 1 TASK: ffffff80802b4e00 CPU: 6 COMMAND: "init" > #0 [ffffffc08006afe0] __switch_to at ffffffc08111d5cc > #1 [ffffffc08006b040] __schedule at ffffffc08111dde0 > #2 [ffffffc08006b0a0] schedule at ffffffc08111e294 > #3 [ffffffc08006b0d0] schedule_preempt_disabled at ffffffc08111e3f0 > #4 [ffffffc08006b140] __mutex_lock at ffffffc08112068c > #5 [ffffffc08006b180] __mutex_lock_slowpath at ffffffc08111f8f8 > #6 [ffffffc08006b1a0] mutex_lock at ffffffc08111f834 > #7 [ffffffc08006b1d0] reclaim_and_purge_vmap_areas at ffffffc0803ebc3c > #8 [ffffffc08006b290] alloc_vmap_area at ffffffc0803e83fc > #9 [ffffffc08006b300] vm_map_ram at ffffffc0803e78c0 > #10 [ffffffc08006b420] z_erofs_lz4_decompress at ffffffc0806a49b0 > #11 [ffffffc08006b670] z_erofs_decompress_queue at ffffffc0806a8fd0 > #12 [ffffffc08006b860] z_erofs_runqueue at ffffffc0806a8744 > #13 [ffffffc08006b970] z_erofs_readahead at ffffffc0806a6cfc > #14 [ffffffc08006ba00] read_pages at ffffffc08037ed78 > #15 [ffffffc08006ba70] page_cache_ra_unbounded at ffffffc08037eb58 > #16 [ffffffc08006bb00] page_cache_ra_order at ffffffc08037f42c > #17 [ffffffc08006bbb0] do_sync_mmap_readahead at ffffffc080371d3c > #18 [ffffffc08006bc40] filemap_fault at ffffffc080371774 > #19 [ffffffc08006bd60] handle_mm_fault at ffffffc0803cc118 > #20 [ffffffc08006bdc0] do_page_fault at ffffffc08112a618 > #21 [ffffffc08006be20] do_translation_fault at ffffffc08112a36c > #22 [ffffffc08006be30] do_mem_abort at ffffffc0800bfbf0 > #23 [ffffffc08006be70] el0_ia at ffffffc08111583c > #24 [ffffffc08006bea0] el0t_64_sync_handler at ffffffc0811156a4 > #25 [ffffffc08006bfe0] el0t_64_sync at ffffffc080091584 > > > > > > > > > > Fixes: fc1e0d980037 ("mm/vmalloc: prevent stale TLBs in fully utilized blocks") > > > > > > Signed-off-by: Zhaoyang Huang > > > --- > > > mm/vmalloc.c | 11 +++++++---- > > > 1 file changed, 7 insertions(+), 4 deletions(-) > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > index 22aa63f4ef63..112b50431725 100644 > > > --- a/mm/vmalloc.c > > > +++ b/mm/vmalloc.c > > > @@ -2614,9 +2614,10 @@ static void free_vmap_block(struct vmap_block *vb) > > > } > > > > > > static bool purge_fragmented_block(struct vmap_block *vb, > > > - struct vmap_block_queue *vbq, struct list_head *purge_list, > > > - bool force_purge) > > > + struct list_head *purge_list, bool force_purge) > > > { > > > + struct vmap_block_queue *vbq; > > > + > > > if (vb->free + vb->dirty != VMAP_BBMAP_BITS || > > > vb->dirty == VMAP_BBMAP_BITS) > > > return false; > > > @@ -2625,6 +2626,8 @@ static bool purge_fragmented_block(struct vmap_block *vb, > > > if (!(force_purge || vb->free < VMAP_PURGE_THRESHOLD)) > > > return false; > > > > > > + vbq = container_of(addr_to_vb_xa(vb->va->va_start), > > > + struct vmap_block_queue, vmap_blocks); > > > /* prevent further allocs after releasing lock */ > > > WRITE_ONCE(vb->free, 0); > > > /* prevent purging it again */ > > > @@ -2664,7 +2667,7 @@ static void purge_fragmented_blocks(int cpu) > > > continue; > > > > > > spin_lock(&vb->lock); > > > - purge_fragmented_block(vb, vbq, &purge, true); > > > + purge_fragmented_block(vb, &purge, true); > > > spin_unlock(&vb->lock); > > > } > > > rcu_read_unlock(); > > > @@ -2801,7 +2804,7 @@ static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush) > > > * not purgeable, check whether there is dirty > > > * space to be flushed. > > > */ > > > - if (!purge_fragmented_block(vb, vbq, &purge_list, false) && > > > + if (!purge_fragmented_block(vb, &purge_list, false) && > > > vb->dirty_max && vb->dirty != VMAP_BBMAP_BITS) { > > > unsigned long va_start = vb->va->va_start; > > > unsigned long s, e; > > > -- > > > 2.25.1 > > > > > > > > >