February 2024 - Linux-stable-mirror

Re: [PATCH 6.1] Backport the fix for CVE-2024-23851 to v6.1

by Greg KH

On Wed, Feb 21, 2024 at 10:52:41AM -0800, He Gao wrote: > I used "git apply" and it required the change. But "patch" can work > directly so yes the original patch works fine. > > In that case, I believe the original patch will also work for 6.6 and 6.7. Great, all done, thanks! greg k-h

1 year

1
0
0 0

[PATCH v2 stable] memcg: add refcnt for pcpu stock to avoid UAF problem in drain_all_stock()

by GONG, Ruiqi

commit 1a3e1f40962c445b997151a542314f3c6097f8c3 upstream. NOTE: This is a partial backport since we only need the refcnt between memcg and stock to fix the problem stated below, and in this way multiple versions use the same code and align with each other. --- There was a kernel panic happened on an in-house environment running 3.10, and the same problem was reproduced on 4.19: general protection fault: 0000 [#1] SMP PTI CPU: 1 PID: 2085 Comm: bash Kdump: loaded Tainted: G L 4.19.90+ #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014 RIP: 0010 drain_all_stock+0xad/0x140 Code: 00 00 4d 85 ff 74 2c 45 85 c9 74 27 4d 39 fc 74 42 41 80 bc 24 28 04 00 00 00 74 17 49 8b 04 24 49 8b 17 48 8b 88 90 02 00 00 <48> 39 8a 90 02 00 00 74 02 eb 86 48 63 88 3c 01 00 00 39 8a 3c 01 RSP: 0018:ffffa7efc5813d70 EFLAGS: 00010202 RAX: ffff8cb185548800 RBX: ffff8cb89f420160 RCX: ffff8cb1867b6000 RDX: babababababababa RSI: 0000000000000001 RDI: 0000000000231876 RBP: 0000000000000000 R08: 0000000000000415 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000001 R12: ffff8cb186f89040 R13: 0000000000020160 R14: 0000000000000001 R15: ffff8cb186b27040 FS: 00007f4a308d3740(0000) GS:ffff8cb89f440000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe4d634a68 CR3: 000000010b022000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: mem_cgroup_force_empty_write+0x31/0xb0 cgroup_file_write+0x60/0x140 ? __check_object_size+0x136/0x147 kernfs_fop_write+0x10e/0x190 __vfs_write+0x37/0x1b0 ? selinux_file_permission+0xe8/0x130 ? security_file_permission+0x2e/0xb0 vfs_write+0xb6/0x1a0 ksys_write+0x57/0xd0 do_syscall_64+0x63/0x250 ? async_page_fault+0x8/0x30 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Modules linked in: ... It is found that in case of stock->nr_pages == 0, the memcg on stock->cached could be freed due to its refcnt decreased to 0, which made stock->cached become a dangling pointer. It could cause a UAF problem in drain_all_stock() in the following concurrent scenario. Note that drain_all_stock() doesn't disable irq but only preemption. CPU1 CPU2 ============================================================================== stock->cached = memcgA (freed) drain_all_stock(memcgB) rcu_read_lock() memcg = CPU1's stock->cached (memcgA) (interrupted) refill_stock(memcgC) drain_stock(memcgA) stock->cached = memcgC stock->nr_pages += xxx (> 0) stock->nr_pages > 0 mem_cgroup_is_descendant(memcgA, memcgB) [UAF] rcu_read_unlock() This problem is, unintentionally, fixed at 5.9, where commit 1a3e1f40962c ("mm: memcontrol: decouple reference counting from page accounting") adds memcg refcnt for stock. Therefore affected LTS versions include 4.19 and 5.4. For 4.19, memcg's css offline process doesn't call drain_all_stock(). so it's easier for the released memcg to be left on the stock. For 5.4, although mem_cgroup_css_offline() does call drain_all_stock(), but the flushing could be skipped when stock->nr_pages happens to be 0, and besides the async draining could be delayed and take place after the UAF problem has happened. Fix this problem by adding (and decreasing) memcg's refcnt when memcg is put onto (and removed from) stock, just like how commit 1a3e1f40962c ("mm: memcontrol: decouple reference counting from page accounting") does. After all, "being on the stock" is a kind of reference with regards to memcg. As such, it's guaranteed that a css on stock would not be freed. It's good to mention that refill_stock() is executed in an irq-disabled context, so the drain_stock() patched with css_put() would not actually free memcgA until the end of refill_stock(), since css_put() is an RCU free and it's still in grace period. For CPU2, the access to CPU1's stock->cached is protected by rcu_read_lock(), so in this case it gets either NULL from stock->cached or a memcgA that is still good. Cc: stable(a)vger.kernel.org # 4.19 5.4 Fixes: cdec2e4265df ("memcg: coalesce charging via percpu storage") Signed-off-by: GONG, Ruiqi <gongruiqi1(a)huawei.com> Acked-by: Michal Hocko <mhocko(a)suse.com> --- v2: - Add a statement of this patch being a partial backport - Add a paragraph to mention the grace period in refill_stock() mm/memcontrol.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5a366cf79821..8c04296df1c7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2015,6 +2015,9 @@ static void drain_stock(struct memcg_stock_pcp *stock) { struct mem_cgroup *old = stock->cached; + if (!old) + return; + if (stock->nr_pages) { page_counter_uncharge(&old->memory, stock->nr_pages); if (do_memsw_account()) @@ -2022,6 +2025,8 @@ static void drain_stock(struct memcg_stock_pcp *stock) css_put_many(&old->css, stock->nr_pages); stock->nr_pages = 0; } + + css_put(&old->css); stock->cached = NULL; } @@ -2057,6 +2062,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) stock = this_cpu_ptr(&memcg_stock); if (stock->cached != memcg) { /* reset if necessary */ drain_stock(stock); + css_get(&memcg->css); stock->cached = memcg; } stock->nr_pages += nr_pages; -- 2.25.1

1 year

1
0
0 0

[PATCH stable] memcg: add refcnt for pcpu stock to avoid UAF problem in drain_all_stock()

by GONG, Ruiqi

commit 1a3e1f40962c445b997151a542314f3c6097f8c3 upstream. There was a kernel panic happened on an in-house environment running 3.10, and the same problem was reproduced on 4.19: general protection fault: 0000 [#1] SMP PTI CPU: 1 PID: 2085 Comm: bash Kdump: loaded Tainted: G L 4.19.90+ #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014 RIP: 0010 drain_all_stock+0xad/0x140 Code: 00 00 4d 85 ff 74 2c 45 85 c9 74 27 4d 39 fc 74 42 41 80 bc 24 28 04 00 00 00 74 17 49 8b 04 24 49 8b 17 48 8b 88 90 02 00 00 <48> 39 8a 90 02 00 00 74 02 eb 86 48 63 88 3c 01 00 00 39 8a 3c 01 RSP: 0018:ffffa7efc5813d70 EFLAGS: 00010202 RAX: ffff8cb185548800 RBX: ffff8cb89f420160 RCX: ffff8cb1867b6000 RDX: babababababababa RSI: 0000000000000001 RDI: 0000000000231876 RBP: 0000000000000000 R08: 0000000000000415 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000001 R12: ffff8cb186f89040 R13: 0000000000020160 R14: 0000000000000001 R15: ffff8cb186b27040 FS: 00007f4a308d3740(0000) GS:ffff8cb89f440000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe4d634a68 CR3: 000000010b022000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: mem_cgroup_force_empty_write+0x31/0xb0 cgroup_file_write+0x60/0x140 ? __check_object_size+0x136/0x147 kernfs_fop_write+0x10e/0x190 __vfs_write+0x37/0x1b0 ? selinux_file_permission+0xe8/0x130 ? security_file_permission+0x2e/0xb0 vfs_write+0xb6/0x1a0 ksys_write+0x57/0xd0 do_syscall_64+0x63/0x250 ? async_page_fault+0x8/0x30 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Modules linked in: ... It is found that in case of stock->nr_pages == 0, the memcg on stock->cached could be freed due to its refcnt decreased to 0, which made stock->cached become a dangling pointer. It could cause a UAF problem in drain_all_stock() in the following concurrent scenario. Note that drain_all_stock() doesn't disable irq but only preemption. CPU1 CPU2 ============================================================================== stock->cached = memcgA (freed) drain_all_stock(memcgB) rcu_read_lock() memcg = CPU1's stock->cached (memcgA) (interrupted) refill_stock(memcgC) drain_stock(memcgA) stock->cached = memcgC stock->nr_pages += xxx (> 0) stock->nr_pages > 0 mem_cgroup_is_descendant(memcgA, memcgB) [UAF] rcu_read_unlock() This problem is, unintenionally, fixed at 5.9, where commit 1a3e1f40962c ("mm: memcontrol: decouple reference counting from page accounting") adds memcg refcnt for stock. Therefore affected LTS versions include 4.19 and 5.4. For 4.19, memcg's css offline process doesn't call drain_all_stock(). so it's easier for the released memcg to be left on the stock. For 5.4, although mem_cgroup_css_offline() does call drain_all_stock(), but the flushing could be skipped when stock->nr_pages happens to be 0, and besides the async draining could be delayed and take place after the UAF problem has happened. Fix this problem by adding (and decreasing) memcg's refcnt when memcg is put onto (and removed from) stock, just like how commit 1a3e1f40962c ("mm: memcontrol: decouple reference counting from page accounting") does. After all, "being on the stock" is a kind of reference with regards to memcg. As such, it's guaranteed that a css on stock would not be freed. Cc: stable(a)vger.kernel.org # 4.19 5.4 Fixes: cdec2e4265df ("memcg: coalesce charging via percpu storage") Signed-off-by: GONG, Ruiqi <gongruiqi1(a)huawei.com> --- mm/memcontrol.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5a366cf79821..8c04296df1c7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2015,6 +2015,9 @@ static void drain_stock(struct memcg_stock_pcp *stock) { struct mem_cgroup *old = stock->cached; + if (!old) + return; + if (stock->nr_pages) { page_counter_uncharge(&old->memory, stock->nr_pages); if (do_memsw_account()) @@ -2022,6 +2025,8 @@ static void drain_stock(struct memcg_stock_pcp *stock) css_put_many(&old->css, stock->nr_pages); stock->nr_pages = 0; } + + css_put(&old->css); stock->cached = NULL; } @@ -2057,6 +2062,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) stock = this_cpu_ptr(&memcg_stock); if (stock->cached != memcg) { /* reset if necessary */ drain_stock(stock); + css_get(&memcg->css); stock->cached = memcg; } stock->nr_pages += nr_pages; -- 2.25.1

1 year

4
9
0 0

[merged mm-stable] kasan-test-avoid-gcc-warning-for-intentional-overflow.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: kasan/test: avoid gcc warning for intentional overflow has been removed from the -mm tree. Its filename was kasan-test-avoid-gcc-warning-for-intentional-overflow.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Arnd Bergmann <arnd(a)arndb.de> Subject: kasan/test: avoid gcc warning for intentional overflow Date: Mon, 12 Feb 2024 12:15:52 +0100 The out-of-bounds test allocates an object that is three bytes too short in order to validate the bounds checking. Starting with gcc-14, this causes a compile-time warning as gcc has grown smart enough to understand the sizeof() logic: mm/kasan/kasan_test.c: In function 'kmalloc_oob_16': mm/kasan/kasan_test.c:443:14: error: allocation of insufficient size '13' for type 'struct <anonymous>' with size '16' [-Werror=alloc-size] 443 | ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL); | ^ Hide the actual computation behind a RELOC_HIDE() that ensures the compiler misses the intentional bug. Link: https://lkml.kernel.org/r/20240212111609.869266-1-arnd@kernel.org Fixes: 3f15801cdc23 ("lib: add kasan test module") Signed-off-by: Arnd Bergmann <arnd(a)arndb.de> Reviewed-by: Andrey Konovalov <andreyknvl(a)gmail.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com> Cc: Arnd Bergmann <arnd(a)arndb.de> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: Marco Elver <elver(a)google.com> Cc: Vincenzo Frascino <vincenzo.frascino(a)arm.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kasan/kasan_test.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/kasan/kasan_test.c~kasan-test-avoid-gcc-warning-for-intentional-overflow +++ a/mm/kasan/kasan_test.c @@ -440,7 +440,8 @@ static void kmalloc_oob_16(struct kunit /* This test is specifically crafted for the generic mode. */ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); - ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL); + /* RELOC_HIDE to prevent gcc from warning about short alloc */ + ptr1 = RELOC_HIDE(kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL), 0); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1); ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL); _ Patches currently in -mm which might be from arnd(a)arndb.de are mm-mmu_gather-add-tlb_remove_tlb_entries-fix.patch

1 year

1
0
0 0

[PATCH ver.2] gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()

by kovalev＠altlinux.org

From: Vasiliy Kovalev <kovalev(a)altlinux.org> The gtp_net_ops pernet operations structure for the subsystem must be registered before registering the generic netlink family. Syzkaller hit 'general protection fault in gtp_genl_dump_pdp' bug: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] CPU: 1 PID: 5826 Comm: gtp Not tainted 6.8.0-rc3-std-def-alt1 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-alt1 04/01/2014 RIP: 0010:gtp_genl_dump_pdp+0x1be/0x800 [gtp] Code: c6 89 c6 e8 64 e9 86 df 58 45 85 f6 0f 85 4e 04 00 00 e8 c5 ee 86 df 48 8b 54 24 18 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 de 05 00 00 48 8b 44 24 18 4c 8b 30 4c 39 f0 74 RSP: 0018:ffff888014107220 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff88800fcda588 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f1be4eb05c0(0000) GS:ffff88806ce80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1be4e766cf CR3: 000000000c33e000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: <TASK> ? show_regs+0x90/0xa0 ? die_addr+0x50/0xd0 ? exc_general_protection+0x148/0x220 ? asm_exc_general_protection+0x22/0x30 ? gtp_genl_dump_pdp+0x1be/0x800 [gtp] ? __alloc_skb+0x1dd/0x350 ? __pfx___alloc_skb+0x10/0x10 genl_dumpit+0x11d/0x230 netlink_dump+0x5b9/0xce0 ? lockdep_hardirqs_on_prepare+0x253/0x430 ? __pfx_netlink_dump+0x10/0x10 ? kasan_save_track+0x10/0x40 ? __kasan_kmalloc+0x9b/0xa0 ? genl_start+0x675/0x970 __netlink_dump_start+0x6fc/0x9f0 genl_family_rcv_msg_dumpit+0x1bb/0x2d0 ? __pfx_genl_family_rcv_msg_dumpit+0x10/0x10 ? genl_op_from_small+0x2a/0x440 ? cap_capable+0x1d0/0x240 ? __pfx_genl_start+0x10/0x10 ? __pfx_genl_dumpit+0x10/0x10 ? __pfx_genl_done+0x10/0x10 ? security_capable+0x9d/0xe0 Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Cc: stable(a)vger.kernel.org Signed-off-by: Vasiliy Kovalev <kovalev(a)altlinux.org> --- drivers/net/gtp.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index b1919278e931f4..2129ae42c70304 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1907,20 +1907,20 @@ static int __init gtp_init(void) if (err < 0) goto error_out; - err = genl_register_family(&gtp_genl_family); + err = register_pernet_subsys(&gtp_net_ops); if (err < 0) goto unreg_rtnl_link; - err = register_pernet_subsys(&gtp_net_ops); + err = genl_register_family(&gtp_genl_family); if (err < 0) - goto unreg_genl_family; + goto unreg_pernet_subsys; pr_info("GTP module loaded (pdp ctx size %zd bytes)\n", sizeof(struct pdp_ctx)); return 0; -unreg_genl_family: - genl_unregister_family(&gtp_genl_family); +unreg_pernet_subsys: + unregister_pernet_subsys(&gtp_net_ops); unreg_rtnl_link: rtnl_link_unregister(&gtp_link_ops); error_out: -- 2.33.8

1 year

4
9
0 0

[PATCH 6.6.y] riscv/efistub: Ensure GP-relative addressing is not used

by Jan Kiszka

From: Jan Kiszka <jan.kiszka(a)siemens.com> commit afb2a4fb84555ef9e61061f6ea63ed7087b295d5 upstream. The cflags for the RISC-V efistub were missing -mno-relax, thus were under the risk that the compiler could use GP-relative addressing. That happened for _edata with binutils-2.41 and kernel 6.1, causing the relocation to fail due to an invalid kernel_size in handle_kernel_image. It was not yet observed with newer versions, but that may just be luck. Cc: <stable(a)vger.kernel.org> Signed-off-by: Jan Kiszka <jan.kiszka(a)siemens.com> Signed-off-by: Ard Biesheuvel <ardb(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/firmware/efi/libstub/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index a1157c2a7170..f54715672d52 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -28,7 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \ -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \ -DEFI_HAVE_STRCMP -fno-builtin -fpic \ $(call cc-option,-mno-single-pic-base) -cflags-$(CONFIG_RISCV) += -fpic +cflags-$(CONFIG_RISCV) += -fpic -mno-relax cflags-$(CONFIG_LOONGARCH) += -fpie cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt -- 2.35.3 -- Siemens AG, Technology Linux Expert Center

1 year

1
0
0 0

[PATCH] pinctrl: qcom: sm8650-lpass-lpi: correct Kconfig name

by Krzysztof Kozlowski

Use proper model name in SM8650 LPASS pin controller Kconfig entry. Cc: <stable(a)vger.kernel.org> Fixes: c4e47673853f ("pinctrl: qcom: sm8650-lpass-lpi: add SM8650 LPASS") Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski(a)linaro.org> --- drivers/pinctrl/qcom/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pinctrl/qcom/Kconfig b/drivers/pinctrl/qcom/Kconfig index e0f2829c15d6..24619e80b2cc 100644 --- a/drivers/pinctrl/qcom/Kconfig +++ b/drivers/pinctrl/qcom/Kconfig @@ -125,7 +125,7 @@ config PINCTRL_SM8550_LPASS_LPI platform. config PINCTRL_SM8650_LPASS_LPI - tristate "Qualcomm Technologies Inc SM8550 LPASS LPI pin controller driver" + tristate "Qualcomm Technologies Inc SM8650 LPASS LPI pin controller driver" depends on ARM64 || COMPILE_TEST depends on PINCTRL_LPASS_LPI help -- 2.34.1

1 year

3
2
0 0

+ mm-vmscan-prevent-infinite-loop-for-costly-gfp_noio-__gfp_retry_mayfail-allocations.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-vmscan-prevent-infinite-loop-for-costly-gfp_noio-__gfp_retry_mayfail-allocations.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… 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: Vlastimil Babka <vbabka(a)suse.cz> Subject: mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations Date: Wed, 21 Feb 2024 12:43:58 +0100 Sven reports an infinite loop in __alloc_pages_slowpath() for costly order __GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination can happen in a suspend/resume context where a GFP_KERNEL allocation can have __GFP_IO masked out via gfp_allowed_mask. Quoting Sven: 1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER) with __GFP_RETRY_MAYFAIL set. 2. page alloc's __alloc_pages_slowpath tries to get a page from the freelist. This fails because there is nothing free of that costly order. 3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim, which bails out because a zone is ready to be compacted; it pretends to have made a single page of progress. 4. page alloc tries to compact, but this always bails out early because __GFP_IO is not set (it's not passed by the snd allocator, and even if it were, we are suspending so the __GFP_IO flag would be cleared anyway). 5. page alloc believes reclaim progress was made (because of the pretense in item 3) and so it checks whether it should retry compaction. The compaction retry logic thinks it should try again, because: a) reclaim is needed because of the early bail-out in item 4 b) a zonelist is suitable for compaction 6. goto 2. indefinite stall. (end quote) The immediate root cause is confusing the COMPACT_SKIPPED returned from __alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be indicating a lack of order-0 pages, and in step 5 evaluating that in should_compact_retry() as a reason to retry, before incrementing and limiting the number of retries. There are however other places that wrongly assume that compaction can happen while we lack __GFP_IO. To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO evaluation and switch the open-coded test in try_to_compact_pages() to use it. Also use the new helper in: - compaction_ready(), which will make reclaim not bail out in step 3, so there's at least one attempt to actually reclaim, even if chances are small for a costly order - in_reclaim_compaction() which will make should_continue_reclaim() return false and we don't over-reclaim unnecessarily - in __alloc_pages_slowpath() to set a local variable can_compact, which is then used to avoid retrying reclaim/compaction for costly allocations (step 5) if we can't compact and also to skip the early compaction attempt that we do in some cases Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"") Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz> Reported-by: Sven van Ashbrook <svenva(a)chromium.org> Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBz… Cc: Brian Geffon <bgeffon(a)google.com> Cc: Curtis Malainey <cujomalainey(a)chromium.org> Cc: Jaroslav Kysela <perex(a)perex.cz> Cc: Mel Gorman <mgorman(a)techsingularity.net> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Takashi Iwai <tiwai(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/gfp.h | 9 +++++++++ mm/compaction.c | 7 +------ mm/page_alloc.c | 10 ++++++---- mm/vmscan.c | 5 ++++- 4 files changed, 20 insertions(+), 11 deletions(-) --- a/include/linux/gfp.h~mm-vmscan-prevent-infinite-loop-for-costly-gfp_noio-__gfp_retry_mayfail-allocations +++ a/include/linux/gfp.h @@ -353,6 +353,15 @@ static inline bool gfp_has_io_fs(gfp_t g return (gfp & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS); } +/* + * Check if the gfp flags allow compaction - GFP_NOIO is a really + * tricky context because the migration might require IO. + */ +static inline bool gfp_compaction_allowed(gfp_t gfp_mask) +{ + return IS_ENABLED(CONFIG_COMPACTION) && (gfp_mask & __GFP_IO); +} + extern gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma); #ifdef CONFIG_CONTIG_ALLOC --- a/mm/compaction.c~mm-vmscan-prevent-infinite-loop-for-costly-gfp_noio-__gfp_retry_mayfail-allocations +++ a/mm/compaction.c @@ -2723,16 +2723,11 @@ enum compact_result try_to_compact_pages unsigned int alloc_flags, const struct alloc_context *ac, enum compact_priority prio, struct page **capture) { - int may_perform_io = (__force int)(gfp_mask & __GFP_IO); struct zoneref *z; struct zone *zone; enum compact_result rc = COMPACT_SKIPPED; - /* - * Check if the GFP flags allow compaction - GFP_NOIO is really - * tricky context because the migration might require IO - */ - if (!may_perform_io) + if (!gfp_compaction_allowed(gfp_mask)) return COMPACT_SKIPPED; trace_mm_compaction_try_to_compact_pages(order, gfp_mask, prio); --- a/mm/page_alloc.c~mm-vmscan-prevent-infinite-loop-for-costly-gfp_noio-__gfp_retry_mayfail-allocations +++ a/mm/page_alloc.c @@ -4041,6 +4041,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, u struct alloc_context *ac) { bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM; + bool can_compact = gfp_compaction_allowed(gfp_mask); const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER; struct page *page = NULL; unsigned int alloc_flags; @@ -4111,7 +4112,7 @@ restart: * Don't try this for allocations that are allowed to ignore * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen. */ - if (can_direct_reclaim && + if (can_direct_reclaim && can_compact && (costly_order || (order > 0 && ac->migratetype != MIGRATE_MOVABLE)) && !gfp_pfmemalloc_allowed(gfp_mask)) { @@ -4209,9 +4210,10 @@ retry: /* * Do not retry costly high order allocations unless they are - * __GFP_RETRY_MAYFAIL + * __GFP_RETRY_MAYFAIL and we can compact */ - if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL)) + if (costly_order && (!can_compact || + !(gfp_mask & __GFP_RETRY_MAYFAIL))) goto nopage; if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, @@ -4224,7 +4226,7 @@ retry: * implementation of the compaction depends on the sufficient amount * of free memory (see __compaction_suitable) */ - if (did_some_progress > 0 && + if (did_some_progress > 0 && can_compact && should_compact_retry(ac, order, alloc_flags, compact_result, &compact_priority, &compaction_retries)) --- a/mm/vmscan.c~mm-vmscan-prevent-infinite-loop-for-costly-gfp_noio-__gfp_retry_mayfail-allocations +++ a/mm/vmscan.c @@ -5753,7 +5753,7 @@ static void shrink_lruvec(struct lruvec /* Use reclaim/compaction for costly allocs or under memory pressure */ static bool in_reclaim_compaction(struct scan_control *sc) { - if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && + if (gfp_compaction_allowed(sc->gfp_mask) && sc->order && (sc->order > PAGE_ALLOC_COSTLY_ORDER || sc->priority < DEF_PRIORITY - 2)) return true; @@ -5998,6 +5998,9 @@ static inline bool compaction_ready(stru { unsigned long watermark; + if (!gfp_compaction_allowed(sc->gfp_mask)) + return false; + /* Allocation can already succeed, nothing to do */ if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone), sc->reclaim_idx, 0)) _ Patches currently in -mm which might be from vbabka(a)suse.cz are mm-vmscan-prevent-infinite-loop-for-costly-gfp_noio-__gfp_retry_mayfail-allocations.patch mm-document-memalloc_noreclaim_save-and-memalloc_pin_save.patch mm-document-memalloc_noreclaim_save-and-memalloc_pin_save-v2.patch

1 year

1
0
0 0

[PATCH 1/3] irqchip/gic-v3-its: Do not assume vPE tables are preallocated

by Oliver Upton

We go through quite a bit of trouble to make sure we pick up any preallocated LPI tables on the redistributors, as enabling LPIs is a one-way switch. There is no such restriction for vLPIs, and for GICv4.1 we expect to allocate a new vPE table at boot. This works as intended when initializing an ITS, however when setting up a redistributor in its_cpu_init_lpis() the early return for preallocated RD tables skips straight past GICv4 setup. This all comes to a head when trying to kexec into a new kernel, as the new kernel silently fails to set up GICv4, leading to a complete loss of SGIs and LPIs for KVM VMs (ouch). Slap a band-aid on the problem by ensuring its_cpu_init_lpis() always initializes GICv4 on the way out, even if the other RD tables were preallocated. Cc: stable(a)vger.kernel.org Fixes: 6479450f72c1 ("irqchip/gic-v4: Fix occasional VLPI drop") Reported-by: George Cherian <gcherian(a)marvell.com> Co-developed-by: Marc Zyngier <maz(a)kernel.org> Signed-off-by: Marc Zyngier <maz(a)kernel.org> Signed-off-by: Oliver Upton <oliver.upton(a)linux.dev> --- I debated a bit on the fixes tag between the blamed commit and commit 5e5168461c22 ("irqchip/gic-v4.1: VPE table (aka GICR_VPROPBASER) allocation"), although it would appear GICv4 could be left in an unknown state after kexec too. drivers/irqchip/irq-gic-v3-its.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index d097001c1e3e..0022852ce494 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -3172,6 +3172,7 @@ static void its_cpu_init_lpis(void) val |= GICR_CTLR_ENABLE_LPIS; writel_relaxed(val, rbase + GICR_CTLR); +out: if (gic_rdists->has_vlpis && !gic_rdists->has_rvpeid) { void __iomem *vlpi_base = gic_data_rdist_vlpi_base(); @@ -3207,7 +3208,6 @@ static void its_cpu_init_lpis(void) /* Make sure the GIC has seen the above */ dsb(sy); -out: gic_data_rdist()->flags |= RD_LOCAL_LPI_ENABLED; pr_info("GICv3: CPU%d: using %s LPI pending table @%pa\n", smp_processor_id(), -- 2.44.0.rc0.258.g7320e95886-goog

1 year

2
1
0 0

[PATCH 0/2] RISC-V: Fix CONFIG_AS_HAS_OPTION_ARCH with tip of tree LLVM

by Nathan Chancellor

Hi all, Eric reported that builds of LLVM with [1] (close to tip of tree) have CONFIG_AS_HAS_OPTION_ARCH=n because the test for expected failure on invalid input has started succeeding. This Kconfig test was added because '.option arch' only causes an assembler warning when it is unsupported, rather than a hard error, which is what users of as-instr expect when something is unsupported. This can be resolved by turning assembler warnings into errors with '-Wa,--fatal-warnings' like we do with the compiler with '-Werror', which is what the first patch does. The second patch removes the invalid test, as the valid test is good enough with fatal warnings. I have diffed several configurations for the different architectures that use as-instr and I have found no issues. I think this could go in through either the kbuild or RISC-V tree with sufficient acks but I will let them fight over who takes it :) [1]: https://github.com/llvm/llvm-project/commit/3ac9fe69f70a2b3541266daedbaaa7d… --- Nathan Chancellor (2): kbuild: Add -Wa,--fatal-warnings to as-instr invocation RISC-V: Drop invalid test from CONFIG_AS_HAS_OPTION_ARCH arch/riscv/Kconfig | 1 - scripts/Kconfig.include | 2 +- scripts/Makefile.compiler | 2 +- 3 files changed, 2 insertions(+), 3 deletions(-) --- base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d change-id: 20240124-fix-riscv-option-arch-llvm-18-3cbe7b09a216 Best regards, -- Nathan Chancellor <nathan(a)kernel.org>

1 year

6
7
0 0

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-stable-mirror February 2024