From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A92A0148832; Fri, 6 Dec 2024 15:05:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733497536; cv=none; b=sfYndNPIub3kS2zWAt35MCsGUx6VlrJZVA46YnkErz8cXbflUHRzRwhi6hvOJzfHBJ4EzV7Wdsh5Z4mR3joIsYoUnLDsPEFDplvbdDT8IG1T/JhpXxH5n5M6u+Kr4UylDpuG+rwk7XmdUVtsf3xB3OISi34Tp2935sb+OB+V9yE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733497536; c=relaxed/simple; bh=SW9SxnU2OheyXRjNi4oOFzTSIx7K8W+ZQF9nmC0EGD0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BDH9faiTF5U9wlabERFN0rT25l5ze+MtT8hcwzot4oWF3zHLQwMRMPGCZ39hYLnINFDbI/o7QvU2fPLwBaFIge+gG9kt1A/U3UO1KOxAir0IJztc0uF9pBjuZIMDI1DjJoaBRUqp2RiN/ResxLFi0DhrQRgKJ7AhsyNmwsmoPIc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bGqNCjS2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bGqNCjS2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12439C4CED1; Fri, 6 Dec 2024 15:05:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1733497536; bh=SW9SxnU2OheyXRjNi4oOFzTSIx7K8W+ZQF9nmC0EGD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bGqNCjS26hD4BVIFzw0NKkJIwY/PVFlPyeLT0gTuQt/m7YpuJ5dDCpWdA4xmKG+bQ rkTzqSgz+Xh9Zl+C1Lh9k1wd7kspCFpcdx8I7qTr1wmgrRk8n3w2p3KD84EcrJZTUF vaSf0eoBy9hYbe6Tt0hZL4uZk/JCZwUfeEZimT7w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kajol Jain , "Nysal Jan K.A" , Michael Ellerman , Sasha Levin Subject: [PATCH 6.6 278/676] powerpc/pseries: Fix dtl_access_lock to be a rw_semaphore Date: Fri, 6 Dec 2024 15:31:37 +0100 Message-ID: <20241206143704.200815346@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241206143653.344873888@linuxfoundation.org> References: <20241206143653.344873888@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Ellerman [ Upstream commit cadae3a45d23aa4f6485938a67cbc47aaaa25e38 ] The dtl_access_lock needs to be a rw_sempahore, a sleeping lock, because the code calls kmalloc() while holding it, which can sleep: # echo 1 > /proc/powerpc/vcpudispatch_stats BUG: sleeping function called from invalid context at include/linux/sched/mm.h:337 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 199, name: sh preempt_count: 1, expected: 0 3 locks held by sh/199: #0: c00000000a0743f8 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x324/0x438 #1: c0000000028c7058 (dtl_enable_mutex){+.+.}-{3:3}, at: vcpudispatch_stats_write+0xd4/0x5f4 #2: c0000000028c70b8 (dtl_access_lock){+.+.}-{2:2}, at: vcpudispatch_stats_write+0x220/0x5f4 CPU: 0 PID: 199 Comm: sh Not tainted 6.10.0-rc4 #152 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries Call Trace: dump_stack_lvl+0x130/0x148 (unreliable) __might_resched+0x174/0x410 kmem_cache_alloc_noprof+0x340/0x3d0 alloc_dtl_buffers+0x124/0x1ac vcpudispatch_stats_write+0x2a8/0x5f4 proc_reg_write+0xf4/0x150 vfs_write+0xfc/0x438 ksys_write+0x88/0x148 system_call_exception+0x1c4/0x5a0 system_call_common+0xf4/0x258 Fixes: 06220d78f24a ("powerpc/pseries: Introduce rwlock to gatekeep DTLB usage") Tested-by: Kajol Jain Reviewed-by: Nysal Jan K.A Reviewed-by: Kajol Jain Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20240819122401.513203-1-mpe@ellerman.id.au Signed-off-by: Sasha Levin --- arch/powerpc/include/asm/dtl.h | 4 ++-- arch/powerpc/platforms/pseries/dtl.c | 8 ++++---- arch/powerpc/platforms/pseries/lpar.c | 8 ++++---- 3 files changed, 10 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/include/asm/dtl.h b/arch/powerpc/include/asm/dtl.h index d6f43d149f8dc..a5c21bc623cb0 100644 --- a/arch/powerpc/include/asm/dtl.h +++ b/arch/powerpc/include/asm/dtl.h @@ -1,8 +1,8 @@ #ifndef _ASM_POWERPC_DTL_H #define _ASM_POWERPC_DTL_H +#include #include -#include /* * Layout of entries in the hypervisor's dispatch trace log buffer. @@ -35,7 +35,7 @@ struct dtl_entry { #define DTL_LOG_ALL (DTL_LOG_CEDE | DTL_LOG_PREEMPT | DTL_LOG_FAULT) extern struct kmem_cache *dtl_cache; -extern rwlock_t dtl_access_lock; +extern struct rw_semaphore dtl_access_lock; extern void register_dtl_buffer(int cpu); extern void alloc_dtl_buffers(unsigned long *time_limit); diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c index 3f1cdccebc9c1..ecc04ef8c53e3 100644 --- a/arch/powerpc/platforms/pseries/dtl.c +++ b/arch/powerpc/platforms/pseries/dtl.c @@ -191,7 +191,7 @@ static int dtl_enable(struct dtl *dtl) return -EBUSY; /* ensure there are no other conflicting dtl users */ - if (!read_trylock(&dtl_access_lock)) + if (!down_read_trylock(&dtl_access_lock)) return -EBUSY; n_entries = dtl_buf_entries; @@ -199,7 +199,7 @@ static int dtl_enable(struct dtl *dtl) if (!buf) { printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n", __func__, dtl->cpu); - read_unlock(&dtl_access_lock); + up_read(&dtl_access_lock); return -ENOMEM; } @@ -217,7 +217,7 @@ static int dtl_enable(struct dtl *dtl) spin_unlock(&dtl->lock); if (rc) { - read_unlock(&dtl_access_lock); + up_read(&dtl_access_lock); kmem_cache_free(dtl_cache, buf); } @@ -232,7 +232,7 @@ static void dtl_disable(struct dtl *dtl) dtl->buf = NULL; dtl->buf_entries = 0; spin_unlock(&dtl->lock); - read_unlock(&dtl_access_lock); + up_read(&dtl_access_lock); } /* file interface */ diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c index c3585e90c6db6..cade33aef4147 100644 --- a/arch/powerpc/platforms/pseries/lpar.c +++ b/arch/powerpc/platforms/pseries/lpar.c @@ -169,7 +169,7 @@ struct vcpu_dispatch_data { */ #define NR_CPUS_H NR_CPUS -DEFINE_RWLOCK(dtl_access_lock); +DECLARE_RWSEM(dtl_access_lock); static DEFINE_PER_CPU(struct vcpu_dispatch_data, vcpu_disp_data); static DEFINE_PER_CPU(u64, dtl_entry_ridx); static DEFINE_PER_CPU(struct dtl_worker, dtl_workers); @@ -463,7 +463,7 @@ static int dtl_worker_enable(unsigned long *time_limit) { int rc = 0, state; - if (!write_trylock(&dtl_access_lock)) { + if (!down_write_trylock(&dtl_access_lock)) { rc = -EBUSY; goto out; } @@ -479,7 +479,7 @@ static int dtl_worker_enable(unsigned long *time_limit) pr_err("vcpudispatch_stats: unable to setup workqueue for DTL processing\n"); free_dtl_buffers(time_limit); reset_global_dtl_mask(); - write_unlock(&dtl_access_lock); + up_write(&dtl_access_lock); rc = -EINVAL; goto out; } @@ -494,7 +494,7 @@ static void dtl_worker_disable(unsigned long *time_limit) cpuhp_remove_state(dtl_worker_state); free_dtl_buffers(time_limit); reset_global_dtl_mask(); - write_unlock(&dtl_access_lock); + up_write(&dtl_access_lock); } static ssize_t vcpudispatch_stats_write(struct file *file, const char __user *p, -- 2.43.0