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* [PATCH 00/44] Change a lot of min_t() that might mask high bits
@ 2025-11-19 22:40 david.laight.linux
  2025-11-19 22:41 ` [PATCH 12/44] block: use min() instead of min_t() david.laight.linux
                   ` (4 more replies)
  0 siblings, 5 replies; 7+ messages in thread
From: david.laight.linux @ 2025-11-19 22:40 UTC (permalink / raw)
  To: linux-kernel
  Cc: Alan Stern, Alexander Viro, Alexei Starovoitov, Andi Shyti,
	Andreas Dilger, Andrew Lunn, Andrew Morton, Andrii Nakryiko,
	Andy Shevchenko, Ard Biesheuvel, Arnaldo Carvalho de Melo,
	Bjorn Helgaas, Borislav Petkov, Christian Brauner,
	Christian König, Christoph Hellwig, Daniel Borkmann,
	Dan Williams, Dave Hansen, Dave Jiang, David Ahern,
	David Hildenbrand, Davidlohr Bueso, David S. Miller, Dennis Zhou,
	Eric Dumazet, Greg Kroah-Hartman, Herbert Xu, Ingo Molnar,
	Jakub Kicinski, Jakub Sitnicki, James E.J. Bottomley,
	Jarkko Sakkinen, Jason A. Donenfeld, Jens Axboe, Jiri Slaby,
	Johannes Weiner, John Allen, Jonathan Cameron, Juergen Gross,
	Kees Cook, KP Singh, Linus Walleij, Martin K. Petersen,
	Matthew Wilcox (Oracle), Mika Westerberg, Mike Rapoport,
	Miklos Szeredi, Namhyung Kim, Neal Cardwell, nic_swsd,
	OGAWA Hirofumi, Olivia Mackall, Paolo Abeni, Paolo Bonzini,
	Peter Huewe, Peter Zijlstra, Rafael J. Wysocki,
	Sean Christopherson, Srinivas Kandagatla, Stefano Stabellini,
	Steven Rostedt, Tejun Heo, Theodore Ts'o, Thomas Gleixner,
	Tom Lendacky, Willem de Bruijn, x86, Yury Norov, amd-gfx, bpf,
	cgroups, dri-devel, io-uring, kvm, linux-acpi, linux-block,
	linux-crypto, linux-cxl, linux-efi, linux-ext4, linux-fsdevel,
	linux-gpio, linux-i2c, linux-integrity, linux-mm, linux-nvme,
	linux-pci, linux-perf-users, linux-scsi, linux-serial,
	linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage,
	David Laight

From: David Laight <david.laight.linux@gmail.com>

It in not uncommon for code to use min_t(uint, a, b) when one of a or b
is 64bit and can have a value that is larger than 2^32;
This is particularly prevelant with:
	uint_var = min_t(uint, uint_var, uint64_expression);

Casts to u8 and u16 are very likely to discard significant bits.

These can be detected at compile time by changing min_t(), for example:
#define CHECK_SIZE(fn, type, val) \
	BUILD_BUG_ON_MSG(sizeof (val) > sizeof (type) && \
		!statically_true(((val) >> 8 * (sizeof (type) - 1)) < 256), \
		fn "() significant bits of '" #val "' may be discarded")

#define min_t(type, x, y) ({ \
	CHECK_SIZE("min_t", type, x); \
	CHECK_SIZE("min_t", type, y); \
	__cmp_once(min, type, x, y); })

(and similar changes to max_t() and clamp_t().)

This shows up some real bugs, some unlikely bugs and some false positives.
In most cases both arguments are unsigned type (just different ones)
and min_t() can just be replaced by min().

The patches are all independant and are most of the ones needed to
get the x86-64 kernel I build to compile.
I've not tried building an allyesconfig or allmodconfig kernel.
I've also not included the patch to minmax.h itself.

I've tried to put the patches that actually fix things first.
The last one is 0009.

I gave up on fixing sched/fair.c - it is too broken for a single patch!
The patch for net/ipv4/tcp.c is also absent because do_tcp_getsockopt()
needs multiple/larger changes to make it 'sane'.

I've had to trim the 124 maintainers/lists that get_maintainer.pl finds
from 124 to under 100 to be able to send the cover letter.
The individual patches only go to the addresses found for the associated files.
That reduces the number of emails to a less unsane number.

David Laight (44):
  x86/asm/bitops: Change the return type of variable__ffs() to unsigned
    int
  ext4: Fix saturation of 64bit inode times for old filesystems
  perf: Fix branch stack callchain limit
  io_uring/net: Change some dubious min_t()
  ipc/msg: Fix saturation of percpu counts in msgctl_info()
  bpf: Verifier, remove some unusual uses of min_t() and max_t()
  net/core/flow_dissector: Fix cap of __skb_flow_dissect() return value.
  net: ethtool: Use min3() instead of nested min_t(u16,...)
  ipv6: __ip6_append_data() don't abuse max_t() casts
  x86/crypto: ctr_crypt() use min() instead of min_t()
  arch/x96/kvm: use min() instead of min_t()
  block: use min() instead of min_t()
  drivers/acpi: use min() instead of min_t()
  drivers/char/hw_random: use min3() instead of nested min_t()
  drivers/char/tpm: use min() instead of min_t()
  drivers/crypto/ccp: use min() instead of min_t()
  drivers/cxl: use min() instead of min_t()
  drivers/gpio: use min() instead of min_t()
  drivers/gpu/drm/amd: use min() instead of min_t()
  drivers/i2c/busses: use min() instead of min_t()
  drivers/net/ethernet/realtek: use min() instead of min_t()
  drivers/nvme: use min() instead of min_t()
  arch/x86/mm: use min() instead of min_t()
  drivers/nvmem: use min() instead of min_t()
  drivers/pci: use min() instead of min_t()
  drivers/scsi: use min() instead of min_t()
  drivers/tty/vt: use umin() instead of min_t(u16, ...) for row/col
    limits
  drivers/usb/storage: use min() instead of min_t()
  drivers/xen: use min() instead of min_t()
  fs: use min() or umin() instead of min_t()
  block: bvec.h: use min() instead of min_t()
  nodemask: use min() instead of min_t()
  ipc: use min() instead of min_t()
  bpf: use min() instead of min_t()
  bpf_trace: use min() instead of min_t()
  lib/bucket_locks: use min() instead of min_t()
  lib/crypto/mpi: use min() instead of min_t()
  lib/dynamic_queue_limits: use max() instead of max_t()
  mm: use min() instead of min_t()
  net: Don't pass bitfields to max_t()
  net/core: Change loop conditions so min() can be used
  net: use min() instead of min_t()
  net/netlink: Use umin() to avoid min_t(int, ...) discarding high bits
  net/mptcp: Change some dubious min_t(int, ...) to min()

 arch/x86/crypto/aesni-intel_glue.c            |  3 +-
 arch/x86/include/asm/bitops.h                 | 18 +++++-------
 arch/x86/kvm/emulate.c                        |  3 +-
 arch/x86/kvm/lapic.c                          |  2 +-
 arch/x86/kvm/mmu/mmu.c                        |  2 +-
 arch/x86/mm/pat/set_memory.c                  | 12 ++++----
 block/blk-iocost.c                            |  6 ++--
 block/blk-settings.c                          |  2 +-
 block/partitions/efi.c                        |  3 +-
 drivers/acpi/property.c                       |  2 +-
 drivers/char/hw_random/core.c                 |  2 +-
 drivers/char/tpm/tpm1-cmd.c                   |  2 +-
 drivers/char/tpm/tpm_tis_core.c               |  4 +--
 drivers/crypto/ccp/ccp-dev.c                  |  2 +-
 drivers/cxl/core/mbox.c                       |  2 +-
 drivers/gpio/gpiolib-acpi-core.c              |  2 +-
 .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c  |  4 +--
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c        |  2 +-
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  2 +-
 drivers/i2c/busses/i2c-designware-master.c    |  2 +-
 drivers/net/ethernet/realtek/r8169_main.c     |  3 +-
 drivers/nvme/host/pci.c                       |  3 +-
 drivers/nvme/host/zns.c                       |  3 +-
 drivers/nvmem/core.c                          |  2 +-
 drivers/pci/probe.c                           |  3 +-
 drivers/scsi/hosts.c                          |  2 +-
 drivers/tty/vt/selection.c                    |  9 +++---
 drivers/usb/storage/protocol.c                |  3 +-
 drivers/xen/grant-table.c                     |  2 +-
 fs/buffer.c                                   |  2 +-
 fs/exec.c                                     |  2 +-
 fs/ext4/ext4.h                                |  2 +-
 fs/ext4/mballoc.c                             |  3 +-
 fs/ext4/resize.c                              |  2 +-
 fs/ext4/super.c                               |  2 +-
 fs/fat/dir.c                                  |  4 +--
 fs/fat/file.c                                 |  3 +-
 fs/fuse/dev.c                                 |  2 +-
 fs/fuse/file.c                                |  8 ++---
 fs/splice.c                                   |  2 +-
 include/linux/bvec.h                          |  3 +-
 include/linux/nodemask.h                      |  9 +++---
 include/linux/perf_event.h                    |  2 +-
 include/net/tcp_ecn.h                         |  5 ++--
 io_uring/net.c                                |  6 ++--
 ipc/mqueue.c                                  |  4 +--
 ipc/msg.c                                     |  6 ++--
 kernel/bpf/core.c                             |  4 +--
 kernel/bpf/log.c                              |  2 +-
 kernel/bpf/verifier.c                         | 29 +++++++------------
 kernel/trace/bpf_trace.c                      |  2 +-
 lib/bucket_locks.c                            |  2 +-
 lib/crypto/mpi/mpicoder.c                     |  2 +-
 lib/dynamic_queue_limits.c                    |  2 +-
 mm/gup.c                                      |  4 +--
 mm/memblock.c                                 |  2 +-
 mm/memory.c                                   |  2 +-
 mm/percpu.c                                   |  2 +-
 mm/truncate.c                                 |  3 +-
 mm/vmscan.c                                   |  2 +-
 net/core/datagram.c                           |  6 ++--
 net/core/flow_dissector.c                     |  7 ++---
 net/core/net-sysfs.c                          |  3 +-
 net/core/skmsg.c                              |  4 +--
 net/ethtool/cmis_cdb.c                        |  7 ++---
 net/ipv4/fib_trie.c                           |  2 +-
 net/ipv4/tcp_input.c                          |  4 +--
 net/ipv4/tcp_output.c                         |  5 ++--
 net/ipv4/tcp_timer.c                          |  4 +--
 net/ipv6/addrconf.c                           |  8 ++---
 net/ipv6/ip6_output.c                         |  7 +++--
 net/ipv6/ndisc.c                              |  5 ++--
 net/mptcp/protocol.c                          |  8 ++---
 net/netlink/genetlink.c                       |  9 +++---
 net/packet/af_packet.c                        |  2 +-
 net/unix/af_unix.c                            |  4 +--
 76 files changed, 141 insertions(+), 176 deletions(-)

-- 
2.39.5


^ permalink raw reply	[flat|nested] 7+ messages in thread

* [PATCH 12/44] block: use min() instead of min_t()
  2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
@ 2025-11-19 22:41 ` david.laight.linux
  2025-11-20 14:44   ` Jens Axboe
  2025-11-20  1:47 ` [PATCH 00/44] Change a lot of min_t() that might mask high bits Jakub Kicinski
                   ` (3 subsequent siblings)
  4 siblings, 1 reply; 7+ messages in thread
From: david.laight.linux @ 2025-11-19 22:41 UTC (permalink / raw)
  To: linux-kernel, cgroups, linux-block, linux-efi
  Cc: Davidlohr Bueso, Jens Axboe, Josef Bacik, Tejun Heo, David Laight

From: David Laight <david.laight.linux@gmail.com>

min_t(unsigned int, a, b) casts an 'unsigned long' to 'unsigned int'.
Use min(a, b) instead as it promotes any 'unsigned int' to 'unsigned long'
and so cannot discard significant bits.

In this case the 'unsigned long' value is small enough that the result
is ok.

(Similarly for max_t() and clamp_t().)

Detected by an extra check added to min_t().

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
 block/blk-iocost.c     | 6 ++----
 block/blk-settings.c   | 2 +-
 block/partitions/efi.c | 3 +--
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 5bfd70311359..a0416927d33d 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -2334,10 +2334,8 @@ static void ioc_timer_fn(struct timer_list *timer)
 			else
 				usage_dur = max_t(u64, now.now - ioc->period_at, 1);
 
-			usage = clamp_t(u32,
-				DIV64_U64_ROUND_UP(usage_us * WEIGHT_ONE,
-						   usage_dur),
-				1, WEIGHT_ONE);
+			usage = clamp(DIV64_U64_ROUND_UP(usage_us * WEIGHT_ONE, usage_dur),
+				      1, WEIGHT_ONE);
 
 			/*
 			 * Already donating or accumulated enough to start.
diff --git a/block/blk-settings.c b/block/blk-settings.c
index d74b13ec8e54..4e0c23e68fac 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -472,7 +472,7 @@ int blk_validate_limits(struct queue_limits *lim)
 		seg_size = lim->max_segment_size;
 	else
 		seg_size = lim->seg_boundary_mask + 1;
-	lim->min_segment_size = min_t(unsigned int, seg_size, PAGE_SIZE);
+	lim->min_segment_size = min(seg_size, PAGE_SIZE);
 
 	/*
 	 * We require drivers to at least do logical block aligned I/O, but
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 7acba66eed48..638261e9f2fb 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -215,8 +215,7 @@ static int is_pmbr_valid(legacy_mbr *mbr, sector_t total_sectors)
 		sz = le32_to_cpu(mbr->partition_record[part].size_in_lba);
 		if (sz != (uint32_t) total_sectors - 1 && sz != 0xFFFFFFFF)
 			pr_debug("GPT: mbr size in lba (%u) different than whole disk (%u).\n",
-				 sz, min_t(uint32_t,
-					   total_sectors - 1, 0xFFFFFFFF));
+				 sz, (uint32_t)min(total_sectors - 1, 0xFFFFFFFF));
 	}
 done:
 	return ret;
-- 
2.39.5


^ permalink raw reply related	[flat|nested] 7+ messages in thread

* Re: [PATCH 00/44] Change a lot of min_t() that might mask high bits
  2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
  2025-11-19 22:41 ` [PATCH 12/44] block: use min() instead of min_t() david.laight.linux
@ 2025-11-20  1:47 ` Jakub Kicinski
  2025-11-20  9:38 ` Lorenzo Stoakes
                   ` (2 subsequent siblings)
  4 siblings, 0 replies; 7+ messages in thread
From: Jakub Kicinski @ 2025-11-20  1:47 UTC (permalink / raw)
  To: david.laight.linux
  Cc: linux-kernel, Alan Stern, Alexander Viro, Alexei Starovoitov,
	Andi Shyti, Andreas Dilger, Andrew Lunn, Andrew Morton,
	Andrii Nakryiko, Andy Shevchenko, Ard Biesheuvel,
	Arnaldo Carvalho de Melo, Bjorn Helgaas, Borislav Petkov,
	Christian Brauner, Christian König, Christoph Hellwig,
	Daniel Borkmann, Dan Williams, Dave Hansen, Dave Jiang,
	David Ahern, David Hildenbrand, Davidlohr Bueso, David S. Miller,
	Dennis Zhou, Eric Dumazet, Greg Kroah-Hartman, Herbert Xu,
	Ingo Molnar, Jakub Sitnicki, James E.J. Bottomley,
	Jarkko Sakkinen, Jason A. Donenfeld, Jens Axboe, Jiri Slaby,
	Johannes Weiner, John Allen, Jonathan Cameron, Juergen Gross,
	Kees Cook, KP Singh, Linus Walleij, Martin K. Petersen,
	Matthew Wilcox (Oracle), Mika Westerberg, Mike Rapoport,
	Miklos Szeredi, Namhyung Kim, Neal Cardwell, nic_swsd,
	OGAWA Hirofumi, Olivia Mackall, Paolo Abeni, Paolo Bonzini,
	Peter Huewe, Peter Zijlstra, Rafael J. Wysocki,
	Sean Christopherson, Srinivas Kandagatla, Stefano Stabellini,
	Steven Rostedt, Tejun Heo, Theodore Ts'o, Thomas Gleixner,
	Tom Lendacky, Willem de Bruijn, x86, Yury Norov, amd-gfx, bpf,
	cgroups, dri-devel, io-uring, kvm, linux-acpi, linux-block,
	linux-crypto, linux-cxl, linux-efi, linux-ext4, linux-fsdevel,
	linux-gpio, linux-i2c, linux-integrity, linux-mm, linux-nvme,
	linux-pci, linux-perf-users, linux-scsi, linux-serial,
	linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage

On Wed, 19 Nov 2025 22:40:56 +0000 david.laight.linux@gmail.com wrote:
> I've had to trim the 124 maintainers/lists that get_maintainer.pl finds
> from 124 to under 100 to be able to send the cover letter.
> The individual patches only go to the addresses found for the associated files.
> That reduces the number of emails to a less unsane number.

Please split the networking (9?) patches out to a separate series.
It will help you with the CC list, and help us to get this applied..

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH 00/44] Change a lot of min_t() that might mask high bits
  2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
  2025-11-19 22:41 ` [PATCH 12/44] block: use min() instead of min_t() david.laight.linux
  2025-11-20  1:47 ` [PATCH 00/44] Change a lot of min_t() that might mask high bits Jakub Kicinski
@ 2025-11-20  9:38 ` Lorenzo Stoakes
  2025-11-20 14:52 ` (subset) " Jens Axboe
  2025-11-24  9:49 ` Herbert Xu
  4 siblings, 0 replies; 7+ messages in thread
From: Lorenzo Stoakes @ 2025-11-20  9:38 UTC (permalink / raw)
  To: david.laight.linux
  Cc: linux-kernel, Alan Stern, Alexander Viro, Alexei Starovoitov,
	Andi Shyti, Andreas Dilger, Andrew Lunn, Andrew Morton,
	Andrii Nakryiko, Andy Shevchenko, Ard Biesheuvel,
	Arnaldo Carvalho de Melo, Bjorn Helgaas, Borislav Petkov,
	Christian Brauner, Christian König, Christoph Hellwig,
	Daniel Borkmann, Dan Williams, Dave Hansen, Dave Jiang,
	David Ahern, David Hildenbrand, Davidlohr Bueso, David S. Miller,
	Dennis Zhou, Eric Dumazet, Greg Kroah-Hartman, Herbert Xu,
	Ingo Molnar, Jakub Kicinski, Jakub Sitnicki, James E.J. Bottomley,
	Jarkko Sakkinen, Jason A. Donenfeld, Jens Axboe, Jiri Slaby,
	Johannes Weiner, John Allen, Jonathan Cameron, Juergen Gross,
	Kees Cook, KP Singh, Linus Walleij, Martin K. Petersen,
	Matthew Wilcox (Oracle), Mika Westerberg, Mike Rapoport,
	Miklos Szeredi, Namhyung Kim, Neal Cardwell, nic_swsd,
	OGAWA Hirofumi, Olivia Mackall, Paolo Abeni, Paolo Bonzini,
	Peter Huewe, Peter Zijlstra, Rafael J. Wysocki,
	Sean Christopherson, Srinivas Kandagatla, Stefano Stabellini,
	Steven Rostedt, Tejun Heo, Theodore Ts'o, Thomas Gleixner,
	Tom Lendacky, Willem de Bruijn, x86, Yury Norov, amd-gfx, bpf,
	cgroups, dri-devel, io-uring, kvm, linux-acpi, linux-block,
	linux-crypto, linux-cxl, linux-efi, linux-ext4, linux-fsdevel,
	linux-gpio, linux-i2c, linux-integrity, linux-mm, linux-nvme,
	linux-pci, linux-perf-users, linux-scsi, linux-serial,
	linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage

On Wed, Nov 19, 2025 at 10:40:56PM +0000, david.laight.linux@gmail.com wrote:
> From: David Laight <david.laight.linux@gmail.com>
>
> It in not uncommon for code to use min_t(uint, a, b) when one of a or b
> is 64bit and can have a value that is larger than 2^32;
> This is particularly prevelant with:
> 	uint_var = min_t(uint, uint_var, uint64_expression);
>
> Casts to u8 and u16 are very likely to discard significant bits.
>
> These can be detected at compile time by changing min_t(), for example:
> #define CHECK_SIZE(fn, type, val) \
> 	BUILD_BUG_ON_MSG(sizeof (val) > sizeof (type) && \
> 		!statically_true(((val) >> 8 * (sizeof (type) - 1)) < 256), \
> 		fn "() significant bits of '" #val "' may be discarded")
>
> #define min_t(type, x, y) ({ \
> 	CHECK_SIZE("min_t", type, x); \
> 	CHECK_SIZE("min_t", type, y); \
> 	__cmp_once(min, type, x, y); })
>
> (and similar changes to max_t() and clamp_t().)

Have we made sure that the introduction of these don't cause a combinatorial
explosion like previous min()/max() changes did?

>
> This shows up some real bugs, some unlikely bugs and some false positives.
> In most cases both arguments are unsigned type (just different ones)
> and min_t() can just be replaced by min().
>
> The patches are all independant and are most of the ones needed to
> get the x86-64 kernel I build to compile.
> I've not tried building an allyesconfig or allmodconfig kernel.

Well I have a beefy box at my disposal so tried thiese for you :)

Both allyesconfig & allmodconfig works fine for x86-64 (I tried both for good
measure)

> I've also not included the patch to minmax.h itself.
>
> I've tried to put the patches that actually fix things first.
> The last one is 0009.
>
> I gave up on fixing sched/fair.c - it is too broken for a single patch!
> The patch for net/ipv4/tcp.c is also absent because do_tcp_getsockopt()
> needs multiple/larger changes to make it 'sane'.

I guess this isn't broken per se there just retain min_t()/max_t() right?

>
> I've had to trim the 124 maintainers/lists that get_maintainer.pl finds
> from 124 to under 100 to be able to send the cover letter.
> The individual patches only go to the addresses found for the associated files.
> That reduces the number of emails to a less unsane number.
>
> David Laight (44):
>   x86/asm/bitops: Change the return type of variable__ffs() to unsigned
>     int
>   ext4: Fix saturation of 64bit inode times for old filesystems
>   perf: Fix branch stack callchain limit
>   io_uring/net: Change some dubious min_t()
>   ipc/msg: Fix saturation of percpu counts in msgctl_info()
>   bpf: Verifier, remove some unusual uses of min_t() and max_t()
>   net/core/flow_dissector: Fix cap of __skb_flow_dissect() return value.
>   net: ethtool: Use min3() instead of nested min_t(u16,...)
>   ipv6: __ip6_append_data() don't abuse max_t() casts
>   x86/crypto: ctr_crypt() use min() instead of min_t()
>   arch/x96/kvm: use min() instead of min_t()
>   block: use min() instead of min_t()
>   drivers/acpi: use min() instead of min_t()
>   drivers/char/hw_random: use min3() instead of nested min_t()
>   drivers/char/tpm: use min() instead of min_t()
>   drivers/crypto/ccp: use min() instead of min_t()
>   drivers/cxl: use min() instead of min_t()
>   drivers/gpio: use min() instead of min_t()
>   drivers/gpu/drm/amd: use min() instead of min_t()
>   drivers/i2c/busses: use min() instead of min_t()
>   drivers/net/ethernet/realtek: use min() instead of min_t()
>   drivers/nvme: use min() instead of min_t()
>   arch/x86/mm: use min() instead of min_t()
>   drivers/nvmem: use min() instead of min_t()
>   drivers/pci: use min() instead of min_t()
>   drivers/scsi: use min() instead of min_t()
>   drivers/tty/vt: use umin() instead of min_t(u16, ...) for row/col
>     limits
>   drivers/usb/storage: use min() instead of min_t()
>   drivers/xen: use min() instead of min_t()
>   fs: use min() or umin() instead of min_t()
>   block: bvec.h: use min() instead of min_t()
>   nodemask: use min() instead of min_t()
>   ipc: use min() instead of min_t()
>   bpf: use min() instead of min_t()
>   bpf_trace: use min() instead of min_t()
>   lib/bucket_locks: use min() instead of min_t()
>   lib/crypto/mpi: use min() instead of min_t()
>   lib/dynamic_queue_limits: use max() instead of max_t()
>   mm: use min() instead of min_t()
>   net: Don't pass bitfields to max_t()
>   net/core: Change loop conditions so min() can be used
>   net: use min() instead of min_t()
>   net/netlink: Use umin() to avoid min_t(int, ...) discarding high bits
>   net/mptcp: Change some dubious min_t(int, ...) to min()
>
>  arch/x86/crypto/aesni-intel_glue.c            |  3 +-
>  arch/x86/include/asm/bitops.h                 | 18 +++++-------
>  arch/x86/kvm/emulate.c                        |  3 +-
>  arch/x86/kvm/lapic.c                          |  2 +-
>  arch/x86/kvm/mmu/mmu.c                        |  2 +-
>  arch/x86/mm/pat/set_memory.c                  | 12 ++++----
>  block/blk-iocost.c                            |  6 ++--
>  block/blk-settings.c                          |  2 +-
>  block/partitions/efi.c                        |  3 +-
>  drivers/acpi/property.c                       |  2 +-
>  drivers/char/hw_random/core.c                 |  2 +-
>  drivers/char/tpm/tpm1-cmd.c                   |  2 +-
>  drivers/char/tpm/tpm_tis_core.c               |  4 +--
>  drivers/crypto/ccp/ccp-dev.c                  |  2 +-
>  drivers/cxl/core/mbox.c                       |  2 +-
>  drivers/gpio/gpiolib-acpi-core.c              |  2 +-
>  .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c  |  4 +--
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c        |  2 +-
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  2 +-
>  drivers/i2c/busses/i2c-designware-master.c    |  2 +-
>  drivers/net/ethernet/realtek/r8169_main.c     |  3 +-
>  drivers/nvme/host/pci.c                       |  3 +-
>  drivers/nvme/host/zns.c                       |  3 +-
>  drivers/nvmem/core.c                          |  2 +-
>  drivers/pci/probe.c                           |  3 +-
>  drivers/scsi/hosts.c                          |  2 +-
>  drivers/tty/vt/selection.c                    |  9 +++---
>  drivers/usb/storage/protocol.c                |  3 +-
>  drivers/xen/grant-table.c                     |  2 +-
>  fs/buffer.c                                   |  2 +-
>  fs/exec.c                                     |  2 +-
>  fs/ext4/ext4.h                                |  2 +-
>  fs/ext4/mballoc.c                             |  3 +-
>  fs/ext4/resize.c                              |  2 +-
>  fs/ext4/super.c                               |  2 +-
>  fs/fat/dir.c                                  |  4 +--
>  fs/fat/file.c                                 |  3 +-
>  fs/fuse/dev.c                                 |  2 +-
>  fs/fuse/file.c                                |  8 ++---
>  fs/splice.c                                   |  2 +-
>  include/linux/bvec.h                          |  3 +-
>  include/linux/nodemask.h                      |  9 +++---
>  include/linux/perf_event.h                    |  2 +-
>  include/net/tcp_ecn.h                         |  5 ++--
>  io_uring/net.c                                |  6 ++--
>  ipc/mqueue.c                                  |  4 +--
>  ipc/msg.c                                     |  6 ++--
>  kernel/bpf/core.c                             |  4 +--
>  kernel/bpf/log.c                              |  2 +-
>  kernel/bpf/verifier.c                         | 29 +++++++------------
>  kernel/trace/bpf_trace.c                      |  2 +-
>  lib/bucket_locks.c                            |  2 +-
>  lib/crypto/mpi/mpicoder.c                     |  2 +-
>  lib/dynamic_queue_limits.c                    |  2 +-
>  mm/gup.c                                      |  4 +--
>  mm/memblock.c                                 |  2 +-
>  mm/memory.c                                   |  2 +-
>  mm/percpu.c                                   |  2 +-
>  mm/truncate.c                                 |  3 +-
>  mm/vmscan.c                                   |  2 +-
>  net/core/datagram.c                           |  6 ++--
>  net/core/flow_dissector.c                     |  7 ++---
>  net/core/net-sysfs.c                          |  3 +-
>  net/core/skmsg.c                              |  4 +--
>  net/ethtool/cmis_cdb.c                        |  7 ++---
>  net/ipv4/fib_trie.c                           |  2 +-
>  net/ipv4/tcp_input.c                          |  4 +--
>  net/ipv4/tcp_output.c                         |  5 ++--
>  net/ipv4/tcp_timer.c                          |  4 +--
>  net/ipv6/addrconf.c                           |  8 ++---
>  net/ipv6/ip6_output.c                         |  7 +++--
>  net/ipv6/ndisc.c                              |  5 ++--
>  net/mptcp/protocol.c                          |  8 ++---
>  net/netlink/genetlink.c                       |  9 +++---
>  net/packet/af_packet.c                        |  2 +-
>  net/unix/af_unix.c                            |  4 +--
>  76 files changed, 141 insertions(+), 176 deletions(-)
>
> --
> 2.39.5
>

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH 12/44] block: use min() instead of min_t()
  2025-11-19 22:41 ` [PATCH 12/44] block: use min() instead of min_t() david.laight.linux
@ 2025-11-20 14:44   ` Jens Axboe
  0 siblings, 0 replies; 7+ messages in thread
From: Jens Axboe @ 2025-11-20 14:44 UTC (permalink / raw)
  To: david.laight.linux, linux-kernel, cgroups, linux-block, linux-efi
  Cc: Davidlohr Bueso, Josef Bacik, Tejun Heo

On 11/19/25 3:41 PM, david.laight.linux@gmail.com wrote:
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index d74b13ec8e54..4e0c23e68fac 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -472,7 +472,7 @@ int blk_validate_limits(struct queue_limits *lim)
>  		seg_size = lim->max_segment_size;
>  	else
>  		seg_size = lim->seg_boundary_mask + 1;
> -	lim->min_segment_size = min_t(unsigned int, seg_size, PAGE_SIZE);
> +	lim->min_segment_size = min(seg_size, PAGE_SIZE);
>  
>  	/*
>  	 * We require drivers to at least do logical block aligned I/O, but

This doesn't exist in the 6.19 branch, dropped.

-- 
Jens Axboe

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: (subset) [PATCH 00/44] Change a lot of min_t() that might mask high bits
  2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
                   ` (2 preceding siblings ...)
  2025-11-20  9:38 ` Lorenzo Stoakes
@ 2025-11-20 14:52 ` Jens Axboe
  2025-11-24  9:49 ` Herbert Xu
  4 siblings, 0 replies; 7+ messages in thread
From: Jens Axboe @ 2025-11-20 14:52 UTC (permalink / raw)
  To: linux-kernel, david.laight.linux
  Cc: Alan Stern, Alexander Viro, Alexei Starovoitov, Andi Shyti,
	Andreas Dilger, Andrew Lunn, Andrew Morton, Andrii Nakryiko,
	Andy Shevchenko, Ard Biesheuvel, Arnaldo Carvalho de Melo,
	Bjorn Helgaas, Borislav Petkov, Christian Brauner,
	Christian König, Christoph Hellwig, Daniel Borkmann,
	Dan Williams, Dave Hansen, Dave Jiang, David Ahern,
	Davidlohr Bueso, David S. Miller, Dennis Zhou, Eric Dumazet,
	Greg Kroah-Hartman, Herbert Xu, Ingo Molnar, Jakub Kicinski,
	Jakub Sitnicki, James E.J. Bottomley, Jarkko Sakkinen,
	Jason A. Donenfeld, Jiri Slaby, Johannes Weiner, John Allen,
	Jonathan Cameron, Juergen Gross, Kees Cook, KP Singh,
	Linus Walleij, Martin K. Petersen, Matthew Wilcox (Oracle),
	Mika Westerberg, Mike Rapoport, Miklos Szeredi, Namhyung Kim,
	Neal Cardwell, nic_swsd, OGAWA Hirofumi, Olivia Mackall,
	Paolo Abeni, Paolo Bonzini, Peter Huewe, Peter Zijlstra,
	Rafael J. Wysocki, Sean Christopherson, Srinivas Kandagatla,
	Stefano Stabellini, Steven Rostedt, Tejun Heo, Theodore Ts'o,
	Thomas Gleixner, Tom Lendacky, Willem de Bruijn, x86, Yury Norov,
	amd-gfx, bpf, cgroups, dri-devel, io-uring, kvm, linux-acpi,
	linux-block, linux-crypto, linux-cxl, linux-efi, linux-ext4,
	linux-fsdevel, linux-gpio, linux-i2c, linux-integrity, linux-mm,
	linux-nvme, linux-pci, linux-perf-users, linux-scsi, linux-serial,
	linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage,
	David Hildenbrand


On Wed, 19 Nov 2025 22:40:56 +0000, david.laight.linux@gmail.com wrote:
> It in not uncommon for code to use min_t(uint, a, b) when one of a or b
> is 64bit and can have a value that is larger than 2^32;
> This is particularly prevelant with:
> 	uint_var = min_t(uint, uint_var, uint64_expression);
> 
> Casts to u8 and u16 are very likely to discard significant bits.
> 
> [...]

Applied, thanks!

[12/44] block: use min() instead of min_t()
        commit: 9420e720ad192c53c8d2803c5a2313b2d586adbd

Best regards,
-- 
Jens Axboe




^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH 00/44] Change a lot of min_t() that might mask high bits
  2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
                   ` (3 preceding siblings ...)
  2025-11-20 14:52 ` (subset) " Jens Axboe
@ 2025-11-24  9:49 ` Herbert Xu
  4 siblings, 0 replies; 7+ messages in thread
From: Herbert Xu @ 2025-11-24  9:49 UTC (permalink / raw)
  To: david.laight.linux
  Cc: linux-kernel, Alan Stern, Alexander Viro, Alexei Starovoitov,
	Andi Shyti, Andreas Dilger, Andrew Lunn, Andrew Morton,
	Andrii Nakryiko, Andy Shevchenko, Ard Biesheuvel,
	Arnaldo Carvalho de Melo, Bjorn Helgaas, Borislav Petkov,
	Christian Brauner, Christian König, Christoph Hellwig,
	Daniel Borkmann, Dan Williams, Dave Hansen, Dave Jiang,
	David Ahern, David Hildenbrand, Davidlohr Bueso, David S. Miller,
	Dennis Zhou, Eric Dumazet, Greg Kroah-Hartman, Ingo Molnar,
	Jakub Kicinski, Jakub Sitnicki, James E.J. Bottomley,
	Jarkko Sakkinen, Jason A. Donenfeld, Jens Axboe, Jiri Slaby,
	Johannes Weiner, John Allen, Jonathan Cameron, Juergen Gross,
	Kees Cook, KP Singh, Linus Walleij, Martin K. Petersen,
	Matthew Wilcox (Oracle), Mika Westerberg, Mike Rapoport,
	Miklos Szeredi, Namhyung Kim, Neal Cardwell, nic_swsd,
	OGAWA Hirofumi, Olivia Mackall, Paolo Abeni, Paolo Bonzini,
	Peter Huewe, Peter Zijlstra, Rafael J. Wysocki,
	Sean Christopherson, Srinivas Kandagatla, Stefano Stabellini,
	Steven Rostedt, Tejun Heo, Theodore Ts'o, Thomas Gleixner,
	Tom Lendacky, Willem de Bruijn, x86, Yury Norov, amd-gfx, bpf,
	cgroups, dri-devel, io-uring, kvm, linux-acpi, linux-block,
	linux-crypto, linux-cxl, linux-efi, linux-ext4, linux-fsdevel,
	linux-gpio, linux-i2c, linux-integrity, linux-mm, linux-nvme,
	linux-pci, linux-perf-users, linux-scsi, linux-serial,
	linux-trace-kernel, linux-usb, mptcp, netdev, usb-storage

On Wed, Nov 19, 2025 at 10:40:56PM +0000, david.laight.linux@gmail.com wrote:
> From: David Laight <david.laight.linux@gmail.com>
> 
> It in not uncommon for code to use min_t(uint, a, b) when one of a or b
> is 64bit and can have a value that is larger than 2^32;
> This is particularly prevelant with:
> 	uint_var = min_t(uint, uint_var, uint64_expression);
> 
> Casts to u8 and u16 are very likely to discard significant bits.
> 
> These can be detected at compile time by changing min_t(), for example:
> #define CHECK_SIZE(fn, type, val) \
> 	BUILD_BUG_ON_MSG(sizeof (val) > sizeof (type) && \
> 		!statically_true(((val) >> 8 * (sizeof (type) - 1)) < 256), \
> 		fn "() significant bits of '" #val "' may be discarded")
> 
> #define min_t(type, x, y) ({ \
> 	CHECK_SIZE("min_t", type, x); \
> 	CHECK_SIZE("min_t", type, y); \
> 	__cmp_once(min, type, x, y); })
> 
> (and similar changes to max_t() and clamp_t().)
> 
> This shows up some real bugs, some unlikely bugs and some false positives.
> In most cases both arguments are unsigned type (just different ones)
> and min_t() can just be replaced by min().
> 
> The patches are all independant and are most of the ones needed to
> get the x86-64 kernel I build to compile.
> I've not tried building an allyesconfig or allmodconfig kernel.
> I've also not included the patch to minmax.h itself.
> 
> I've tried to put the patches that actually fix things first.
> The last one is 0009.
> 
> I gave up on fixing sched/fair.c - it is too broken for a single patch!
> The patch for net/ipv4/tcp.c is also absent because do_tcp_getsockopt()
> needs multiple/larger changes to make it 'sane'.
> 
> I've had to trim the 124 maintainers/lists that get_maintainer.pl finds
> from 124 to under 100 to be able to send the cover letter.
> The individual patches only go to the addresses found for the associated files.
> That reduces the number of emails to a less unsane number.
> 
> David Laight (44):
>   x86/asm/bitops: Change the return type of variable__ffs() to unsigned
>     int
>   ext4: Fix saturation of 64bit inode times for old filesystems
>   perf: Fix branch stack callchain limit
>   io_uring/net: Change some dubious min_t()
>   ipc/msg: Fix saturation of percpu counts in msgctl_info()
>   bpf: Verifier, remove some unusual uses of min_t() and max_t()
>   net/core/flow_dissector: Fix cap of __skb_flow_dissect() return value.
>   net: ethtool: Use min3() instead of nested min_t(u16,...)
>   ipv6: __ip6_append_data() don't abuse max_t() casts
>   x86/crypto: ctr_crypt() use min() instead of min_t()
>   arch/x96/kvm: use min() instead of min_t()
>   block: use min() instead of min_t()
>   drivers/acpi: use min() instead of min_t()
>   drivers/char/hw_random: use min3() instead of nested min_t()
>   drivers/char/tpm: use min() instead of min_t()
>   drivers/crypto/ccp: use min() instead of min_t()
>   drivers/cxl: use min() instead of min_t()
>   drivers/gpio: use min() instead of min_t()
>   drivers/gpu/drm/amd: use min() instead of min_t()
>   drivers/i2c/busses: use min() instead of min_t()
>   drivers/net/ethernet/realtek: use min() instead of min_t()
>   drivers/nvme: use min() instead of min_t()
>   arch/x86/mm: use min() instead of min_t()
>   drivers/nvmem: use min() instead of min_t()
>   drivers/pci: use min() instead of min_t()
>   drivers/scsi: use min() instead of min_t()
>   drivers/tty/vt: use umin() instead of min_t(u16, ...) for row/col
>     limits
>   drivers/usb/storage: use min() instead of min_t()
>   drivers/xen: use min() instead of min_t()
>   fs: use min() or umin() instead of min_t()
>   block: bvec.h: use min() instead of min_t()
>   nodemask: use min() instead of min_t()
>   ipc: use min() instead of min_t()
>   bpf: use min() instead of min_t()
>   bpf_trace: use min() instead of min_t()
>   lib/bucket_locks: use min() instead of min_t()
>   lib/crypto/mpi: use min() instead of min_t()
>   lib/dynamic_queue_limits: use max() instead of max_t()
>   mm: use min() instead of min_t()
>   net: Don't pass bitfields to max_t()
>   net/core: Change loop conditions so min() can be used
>   net: use min() instead of min_t()
>   net/netlink: Use umin() to avoid min_t(int, ...) discarding high bits
>   net/mptcp: Change some dubious min_t(int, ...) to min()
> 
>  arch/x86/crypto/aesni-intel_glue.c            |  3 +-
>  arch/x86/include/asm/bitops.h                 | 18 +++++-------
>  arch/x86/kvm/emulate.c                        |  3 +-
>  arch/x86/kvm/lapic.c                          |  2 +-
>  arch/x86/kvm/mmu/mmu.c                        |  2 +-
>  arch/x86/mm/pat/set_memory.c                  | 12 ++++----
>  block/blk-iocost.c                            |  6 ++--
>  block/blk-settings.c                          |  2 +-
>  block/partitions/efi.c                        |  3 +-
>  drivers/acpi/property.c                       |  2 +-
>  drivers/char/hw_random/core.c                 |  2 +-
>  drivers/char/tpm/tpm1-cmd.c                   |  2 +-
>  drivers/char/tpm/tpm_tis_core.c               |  4 +--
>  drivers/crypto/ccp/ccp-dev.c                  |  2 +-
>  drivers/cxl/core/mbox.c                       |  2 +-
>  drivers/gpio/gpiolib-acpi-core.c              |  2 +-
>  .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c  |  4 +--
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c        |  2 +-
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  2 +-
>  drivers/i2c/busses/i2c-designware-master.c    |  2 +-
>  drivers/net/ethernet/realtek/r8169_main.c     |  3 +-
>  drivers/nvme/host/pci.c                       |  3 +-
>  drivers/nvme/host/zns.c                       |  3 +-
>  drivers/nvmem/core.c                          |  2 +-
>  drivers/pci/probe.c                           |  3 +-
>  drivers/scsi/hosts.c                          |  2 +-
>  drivers/tty/vt/selection.c                    |  9 +++---
>  drivers/usb/storage/protocol.c                |  3 +-
>  drivers/xen/grant-table.c                     |  2 +-
>  fs/buffer.c                                   |  2 +-
>  fs/exec.c                                     |  2 +-
>  fs/ext4/ext4.h                                |  2 +-
>  fs/ext4/mballoc.c                             |  3 +-
>  fs/ext4/resize.c                              |  2 +-
>  fs/ext4/super.c                               |  2 +-
>  fs/fat/dir.c                                  |  4 +--
>  fs/fat/file.c                                 |  3 +-
>  fs/fuse/dev.c                                 |  2 +-
>  fs/fuse/file.c                                |  8 ++---
>  fs/splice.c                                   |  2 +-
>  include/linux/bvec.h                          |  3 +-
>  include/linux/nodemask.h                      |  9 +++---
>  include/linux/perf_event.h                    |  2 +-
>  include/net/tcp_ecn.h                         |  5 ++--
>  io_uring/net.c                                |  6 ++--
>  ipc/mqueue.c                                  |  4 +--
>  ipc/msg.c                                     |  6 ++--
>  kernel/bpf/core.c                             |  4 +--
>  kernel/bpf/log.c                              |  2 +-
>  kernel/bpf/verifier.c                         | 29 +++++++------------
>  kernel/trace/bpf_trace.c                      |  2 +-
>  lib/bucket_locks.c                            |  2 +-
>  lib/crypto/mpi/mpicoder.c                     |  2 +-
>  lib/dynamic_queue_limits.c                    |  2 +-
>  mm/gup.c                                      |  4 +--
>  mm/memblock.c                                 |  2 +-
>  mm/memory.c                                   |  2 +-
>  mm/percpu.c                                   |  2 +-
>  mm/truncate.c                                 |  3 +-
>  mm/vmscan.c                                   |  2 +-
>  net/core/datagram.c                           |  6 ++--
>  net/core/flow_dissector.c                     |  7 ++---
>  net/core/net-sysfs.c                          |  3 +-
>  net/core/skmsg.c                              |  4 +--
>  net/ethtool/cmis_cdb.c                        |  7 ++---
>  net/ipv4/fib_trie.c                           |  2 +-
>  net/ipv4/tcp_input.c                          |  4 +--
>  net/ipv4/tcp_output.c                         |  5 ++--
>  net/ipv4/tcp_timer.c                          |  4 +--
>  net/ipv6/addrconf.c                           |  8 ++---
>  net/ipv6/ip6_output.c                         |  7 +++--
>  net/ipv6/ndisc.c                              |  5 ++--
>  net/mptcp/protocol.c                          |  8 ++---
>  net/netlink/genetlink.c                       |  9 +++---
>  net/packet/af_packet.c                        |  2 +-
>  net/unix/af_unix.c                            |  4 +--
>  76 files changed, 141 insertions(+), 176 deletions(-)

Patches 10,14,16,37 applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2025-11-24  9:54 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
2025-11-19 22:41 ` [PATCH 12/44] block: use min() instead of min_t() david.laight.linux
2025-11-20 14:44   ` Jens Axboe
2025-11-20  1:47 ` [PATCH 00/44] Change a lot of min_t() that might mask high bits Jakub Kicinski
2025-11-20  9:38 ` Lorenzo Stoakes
2025-11-20 14:52 ` (subset) " Jens Axboe
2025-11-24  9:49 ` Herbert Xu

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