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[PATCH v3] hfsplus: return error when node already exists in hfs_bnode_create

by Shardul Bankar

When hfs_bnode_create() finds that a node is already hashed (which should not happen in normal operation), it currently returns the existing node without incrementing its reference count. This causes a reference count inconsistency that leads to a kernel panic when the node is later freed in hfs_bnode_put(): kernel BUG at fs/hfsplus/bnode.c:676! BUG_ON(!atomic_read(&node->refcnt)) This scenario can occur when hfs_bmap_alloc() attempts to allocate a node that is already in use (e.g., when node 0's bitmap bit is incorrectly unset), or due to filesystem corruption. Returning an existing node from a create path is not normal operation. Fix this by returning ERR_PTR(-EEXIST) instead of the node when it's already hashed. This properly signals the error condition to callers, which already check for IS_ERR() return values. Reported-by: syzbot+1c8ff72d0cd8a50dfeaa(a)syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=1c8ff72d0cd8a50dfeaa Link: https://lore.kernel.org/all/784415834694f39902088fa8946850fc1779a318.camel@… Fixes: 634725a92938 ("[PATCH] hfs: cleanup HFS+ prints") Signed-off-by: Shardul Bankar <shardul.b(a)mpiricsoftware.com> --- v3 changes: - This is posted standalone as discussed in the v2 thread. v2 changes: - Implement Slava's suggestion: return ERR_PTR(-EEXIST) for already-hashed nodes. - Keep the node-0 allocation guard as a minimal, targeted hardening measure. fs/hfsplus/bnode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/hfsplus/bnode.c b/fs/hfsplus/bnode.c index 191661af9677..250a226336ea 100644 --- a/fs/hfsplus/bnode.c +++ b/fs/hfsplus/bnode.c @@ -629,7 +629,7 @@ struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num) if (node) { pr_crit("new node %u already hashed?\n", num); WARN_ON(1); - return node; + return ERR_PTR(-EEXIST); } node = __hfs_bnode_create(tree, num); if (!node) -- 2.34.1

1 week, 3 days

FAILED: patch "[PATCH] btrfs: don't rewrite ret from inode_permission" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

1 week, 3 days

FAILED: patch "[PATCH] btrfs: don't rewrite ret from inode_permission" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

1 week, 3 days

FAILED: patch "[PATCH] wifi: mt76: Fix DTS power-limits on little endian systems" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 38b845e1f9e810869b0a0b69f202b877b7b7fb12 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122937-ninetieth-giddiness-50de@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 38b845e1f9e810869b0a0b69f202b877b7b7fb12 Mon Sep 17 00:00:00 2001 From: "Sven Eckelmann (Plasma Cloud)" <se(a)simonwunderlich.de> Date: Fri, 26 Sep 2025 11:32:54 +0200 Subject: [PATCH] wifi: mt76: Fix DTS power-limits on little endian systems The power-limits for ru and mcs and stored in the devicetree as bytewise array (often with sizes which are not a multiple of 4). These arrays have a prefix which defines for how many modes a line is applied. This prefix is also only a byte - but the code still tried to fix the endianness of this byte with a be32 operation. As result, loading was mostly failing or was sending completely unexpected values to the firmware. Since the other rates are also stored in the devicetree as bytewise arrays, just drop the u32 access + be32_to_cpu conversion and directly access them as bytes arrays. Cc: stable(a)vger.kernel.org Fixes: 22b980badc0f ("mt76: add functions for parsing rate power limits from DT") Fixes: a9627d992b5e ("mt76: extend DT rate power limits to support 11ax devices") Signed-off-by: Sven Eckelmann (Plasma Cloud) <se(a)simonwunderlich.de> Signed-off-by: Felix Fietkau <nbd(a)nbd.name> diff --git a/drivers/net/wireless/mediatek/mt76/eeprom.c b/drivers/net/wireless/mediatek/mt76/eeprom.c index a987c5e4eff6..6ce8e4af18fe 100644 --- a/drivers/net/wireless/mediatek/mt76/eeprom.c +++ b/drivers/net/wireless/mediatek/mt76/eeprom.c @@ -253,6 +253,19 @@ mt76_get_of_array(struct device_node *np, char *name, size_t *len, int min) return prop->value; } +static const s8 * +mt76_get_of_array_s8(struct device_node *np, char *name, size_t *len, int min) +{ + struct property *prop = of_find_property(np, name, NULL); + + if (!prop || !prop->value || prop->length < min) + return NULL; + + *len = prop->length; + + return prop->value; +} + struct device_node * mt76_find_channel_node(struct device_node *np, struct ieee80211_channel *chan) { @@ -294,7 +307,7 @@ mt76_get_txs_delta(struct device_node *np, u8 nss) } static void -mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const __be32 *data, +mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const s8 *data, s8 target_power, s8 nss_delta, s8 *max_power) { int i; @@ -303,15 +316,14 @@ mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const __be32 *data, return; for (i = 0; i < pwr_len; i++) { - pwr[i] = min_t(s8, target_power, - be32_to_cpu(data[i]) + nss_delta); + pwr[i] = min_t(s8, target_power, data[i] + nss_delta); *max_power = max(*max_power, pwr[i]); } } static void mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, - const __be32 *data, size_t len, s8 target_power, + const s8 *data, size_t len, s8 target_power, s8 nss_delta, s8 *max_power) { int i, cur; @@ -319,8 +331,7 @@ mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, if (!data) return; - len /= 4; - cur = be32_to_cpu(data[0]); + cur = data[0]; for (i = 0; i < pwr_num; i++) { if (len < pwr_len + 1) break; @@ -335,7 +346,7 @@ mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, if (!len) break; - cur = be32_to_cpu(data[0]); + cur = data[0]; } } @@ -346,7 +357,7 @@ s8 mt76_get_rate_power_limits(struct mt76_phy *phy, { struct mt76_dev *dev = phy->dev; struct device_node *np; - const __be32 *val; + const s8 *val; char name[16]; u32 mcs_rates = dev->drv->mcs_rates; u32 ru_rates = ARRAY_SIZE(dest->ru[0]); @@ -392,21 +403,21 @@ s8 mt76_get_rate_power_limits(struct mt76_phy *phy, txs_delta = mt76_get_txs_delta(np, hweight16(phy->chainmask)); - val = mt76_get_of_array(np, "rates-cck", &len, ARRAY_SIZE(dest->cck)); + val = mt76_get_of_array_s8(np, "rates-cck", &len, ARRAY_SIZE(dest->cck)); mt76_apply_array_limit(dest->cck, ARRAY_SIZE(dest->cck), val, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-ofdm", - &len, ARRAY_SIZE(dest->ofdm)); + val = mt76_get_of_array_s8(np, "rates-ofdm", + &len, ARRAY_SIZE(dest->ofdm)); mt76_apply_array_limit(dest->ofdm, ARRAY_SIZE(dest->ofdm), val, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-mcs", &len, mcs_rates + 1); + val = mt76_get_of_array_s8(np, "rates-mcs", &len, mcs_rates + 1); mt76_apply_multi_array_limit(dest->mcs[0], ARRAY_SIZE(dest->mcs[0]), ARRAY_SIZE(dest->mcs), val, len, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-ru", &len, ru_rates + 1); + val = mt76_get_of_array_s8(np, "rates-ru", &len, ru_rates + 1); mt76_apply_multi_array_limit(dest->ru[0], ARRAY_SIZE(dest->ru[0]), ARRAY_SIZE(dest->ru), val, len, target_power, txs_delta, &max_power);

1 week, 3 days

FAILED: patch "[PATCH] btrfs: don't rewrite ret from inode_permission" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

1 week, 3 days

FAILED: patch "[PATCH] btrfs: don't rewrite ret from inode_permission" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

1 week, 3 days

FAILED: patch "[PATCH] wifi: mt76: Fix DTS power-limits on little endian systems" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 38b845e1f9e810869b0a0b69f202b877b7b7fb12 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122936-impotence-sandworm-9ea8@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 38b845e1f9e810869b0a0b69f202b877b7b7fb12 Mon Sep 17 00:00:00 2001 From: "Sven Eckelmann (Plasma Cloud)" <se(a)simonwunderlich.de> Date: Fri, 26 Sep 2025 11:32:54 +0200 Subject: [PATCH] wifi: mt76: Fix DTS power-limits on little endian systems The power-limits for ru and mcs and stored in the devicetree as bytewise array (often with sizes which are not a multiple of 4). These arrays have a prefix which defines for how many modes a line is applied. This prefix is also only a byte - but the code still tried to fix the endianness of this byte with a be32 operation. As result, loading was mostly failing or was sending completely unexpected values to the firmware. Since the other rates are also stored in the devicetree as bytewise arrays, just drop the u32 access + be32_to_cpu conversion and directly access them as bytes arrays. Cc: stable(a)vger.kernel.org Fixes: 22b980badc0f ("mt76: add functions for parsing rate power limits from DT") Fixes: a9627d992b5e ("mt76: extend DT rate power limits to support 11ax devices") Signed-off-by: Sven Eckelmann (Plasma Cloud) <se(a)simonwunderlich.de> Signed-off-by: Felix Fietkau <nbd(a)nbd.name> diff --git a/drivers/net/wireless/mediatek/mt76/eeprom.c b/drivers/net/wireless/mediatek/mt76/eeprom.c index a987c5e4eff6..6ce8e4af18fe 100644 --- a/drivers/net/wireless/mediatek/mt76/eeprom.c +++ b/drivers/net/wireless/mediatek/mt76/eeprom.c @@ -253,6 +253,19 @@ mt76_get_of_array(struct device_node *np, char *name, size_t *len, int min) return prop->value; } +static const s8 * +mt76_get_of_array_s8(struct device_node *np, char *name, size_t *len, int min) +{ + struct property *prop = of_find_property(np, name, NULL); + + if (!prop || !prop->value || prop->length < min) + return NULL; + + *len = prop->length; + + return prop->value; +} + struct device_node * mt76_find_channel_node(struct device_node *np, struct ieee80211_channel *chan) { @@ -294,7 +307,7 @@ mt76_get_txs_delta(struct device_node *np, u8 nss) } static void -mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const __be32 *data, +mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const s8 *data, s8 target_power, s8 nss_delta, s8 *max_power) { int i; @@ -303,15 +316,14 @@ mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const __be32 *data, return; for (i = 0; i < pwr_len; i++) { - pwr[i] = min_t(s8, target_power, - be32_to_cpu(data[i]) + nss_delta); + pwr[i] = min_t(s8, target_power, data[i] + nss_delta); *max_power = max(*max_power, pwr[i]); } } static void mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, - const __be32 *data, size_t len, s8 target_power, + const s8 *data, size_t len, s8 target_power, s8 nss_delta, s8 *max_power) { int i, cur; @@ -319,8 +331,7 @@ mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, if (!data) return; - len /= 4; - cur = be32_to_cpu(data[0]); + cur = data[0]; for (i = 0; i < pwr_num; i++) { if (len < pwr_len + 1) break; @@ -335,7 +346,7 @@ mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, if (!len) break; - cur = be32_to_cpu(data[0]); + cur = data[0]; } } @@ -346,7 +357,7 @@ s8 mt76_get_rate_power_limits(struct mt76_phy *phy, { struct mt76_dev *dev = phy->dev; struct device_node *np; - const __be32 *val; + const s8 *val; char name[16]; u32 mcs_rates = dev->drv->mcs_rates; u32 ru_rates = ARRAY_SIZE(dest->ru[0]); @@ -392,21 +403,21 @@ s8 mt76_get_rate_power_limits(struct mt76_phy *phy, txs_delta = mt76_get_txs_delta(np, hweight16(phy->chainmask)); - val = mt76_get_of_array(np, "rates-cck", &len, ARRAY_SIZE(dest->cck)); + val = mt76_get_of_array_s8(np, "rates-cck", &len, ARRAY_SIZE(dest->cck)); mt76_apply_array_limit(dest->cck, ARRAY_SIZE(dest->cck), val, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-ofdm", - &len, ARRAY_SIZE(dest->ofdm)); + val = mt76_get_of_array_s8(np, "rates-ofdm", + &len, ARRAY_SIZE(dest->ofdm)); mt76_apply_array_limit(dest->ofdm, ARRAY_SIZE(dest->ofdm), val, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-mcs", &len, mcs_rates + 1); + val = mt76_get_of_array_s8(np, "rates-mcs", &len, mcs_rates + 1); mt76_apply_multi_array_limit(dest->mcs[0], ARRAY_SIZE(dest->mcs[0]), ARRAY_SIZE(dest->mcs), val, len, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-ru", &len, ru_rates + 1); + val = mt76_get_of_array_s8(np, "rates-ru", &len, ru_rates + 1); mt76_apply_multi_array_limit(dest->ru[0], ARRAY_SIZE(dest->ru[0]), ARRAY_SIZE(dest->ru), val, len, target_power, txs_delta, &max_power);

1 week, 3 days

[PATCH v2] ARM: dts: integrator: Fix DMA ranges mismatch warning on IM-PD1

by Kuan-Wei Chiu

When compiling the device tree for the Integrator/AP with IM-PD1, the following warning is observed regarding the display controller node: arch/arm/boot/dts/arm/integratorap-im-pd1.dts:251.3-14: Warning (dma_ranges_format): /bus@c0000000/bus@c0000000/display@1000000:dma-ranges: empty "dma-ranges" property but its #address-cells (2) differs from /bus@c0000000/bus@c0000000 (1) The "dma-ranges" property is intended to describe DMA address translations for child nodes. However, the only child of the display controller is a "port" node, which does not perform DMA memory accesses. Since the property is not required for the child node and triggers a warning due to default address cell mismatch, remove it. Fixes: 7bea67a99430 ("ARM: dts: integrator: Fix DMA ranges") Cc: stable(a)vger.kernel.org Signed-off-by: Kuan-Wei Chiu <visitorckw(a)gmail.com> --- Changes in v2: - Switch approach to remove the unused "dma-ranges" property instead of adding "#address-cells" and "#size-cells". arch/arm/boot/dts/arm/integratorap-im-pd1.dts | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/arm/boot/dts/arm/integratorap-im-pd1.dts b/arch/arm/boot/dts/arm/integratorap-im-pd1.dts index db13e09f2fab..0e568baf03b0 100644 --- a/arch/arm/boot/dts/arm/integratorap-im-pd1.dts +++ b/arch/arm/boot/dts/arm/integratorap-im-pd1.dts @@ -248,7 +248,6 @@ display@1000000 { /* 640x480 16bpp @ 25.175MHz is 36827428 bytes/s */ max-memory-bandwidth = <40000000>; memory-region = <&impd1_ram>; - dma-ranges; port@0 { #address-cells = <1>; -- 2.52.0.358.g0dd7633a29-goog

1 week, 3 days

FAILED: patch "[PATCH] wifi: mt76: Fix DTS power-limits on little endian systems" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 38b845e1f9e810869b0a0b69f202b877b7b7fb12 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122936-python-fidgeting-f6f4@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 38b845e1f9e810869b0a0b69f202b877b7b7fb12 Mon Sep 17 00:00:00 2001 From: "Sven Eckelmann (Plasma Cloud)" <se(a)simonwunderlich.de> Date: Fri, 26 Sep 2025 11:32:54 +0200 Subject: [PATCH] wifi: mt76: Fix DTS power-limits on little endian systems The power-limits for ru and mcs and stored in the devicetree as bytewise array (often with sizes which are not a multiple of 4). These arrays have a prefix which defines for how many modes a line is applied. This prefix is also only a byte - but the code still tried to fix the endianness of this byte with a be32 operation. As result, loading was mostly failing or was sending completely unexpected values to the firmware. Since the other rates are also stored in the devicetree as bytewise arrays, just drop the u32 access + be32_to_cpu conversion and directly access them as bytes arrays. Cc: stable(a)vger.kernel.org Fixes: 22b980badc0f ("mt76: add functions for parsing rate power limits from DT") Fixes: a9627d992b5e ("mt76: extend DT rate power limits to support 11ax devices") Signed-off-by: Sven Eckelmann (Plasma Cloud) <se(a)simonwunderlich.de> Signed-off-by: Felix Fietkau <nbd(a)nbd.name> diff --git a/drivers/net/wireless/mediatek/mt76/eeprom.c b/drivers/net/wireless/mediatek/mt76/eeprom.c index a987c5e4eff6..6ce8e4af18fe 100644 --- a/drivers/net/wireless/mediatek/mt76/eeprom.c +++ b/drivers/net/wireless/mediatek/mt76/eeprom.c @@ -253,6 +253,19 @@ mt76_get_of_array(struct device_node *np, char *name, size_t *len, int min) return prop->value; } +static const s8 * +mt76_get_of_array_s8(struct device_node *np, char *name, size_t *len, int min) +{ + struct property *prop = of_find_property(np, name, NULL); + + if (!prop || !prop->value || prop->length < min) + return NULL; + + *len = prop->length; + + return prop->value; +} + struct device_node * mt76_find_channel_node(struct device_node *np, struct ieee80211_channel *chan) { @@ -294,7 +307,7 @@ mt76_get_txs_delta(struct device_node *np, u8 nss) } static void -mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const __be32 *data, +mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const s8 *data, s8 target_power, s8 nss_delta, s8 *max_power) { int i; @@ -303,15 +316,14 @@ mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const __be32 *data, return; for (i = 0; i < pwr_len; i++) { - pwr[i] = min_t(s8, target_power, - be32_to_cpu(data[i]) + nss_delta); + pwr[i] = min_t(s8, target_power, data[i] + nss_delta); *max_power = max(*max_power, pwr[i]); } } static void mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, - const __be32 *data, size_t len, s8 target_power, + const s8 *data, size_t len, s8 target_power, s8 nss_delta, s8 *max_power) { int i, cur; @@ -319,8 +331,7 @@ mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, if (!data) return; - len /= 4; - cur = be32_to_cpu(data[0]); + cur = data[0]; for (i = 0; i < pwr_num; i++) { if (len < pwr_len + 1) break; @@ -335,7 +346,7 @@ mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num, if (!len) break; - cur = be32_to_cpu(data[0]); + cur = data[0]; } } @@ -346,7 +357,7 @@ s8 mt76_get_rate_power_limits(struct mt76_phy *phy, { struct mt76_dev *dev = phy->dev; struct device_node *np; - const __be32 *val; + const s8 *val; char name[16]; u32 mcs_rates = dev->drv->mcs_rates; u32 ru_rates = ARRAY_SIZE(dest->ru[0]); @@ -392,21 +403,21 @@ s8 mt76_get_rate_power_limits(struct mt76_phy *phy, txs_delta = mt76_get_txs_delta(np, hweight16(phy->chainmask)); - val = mt76_get_of_array(np, "rates-cck", &len, ARRAY_SIZE(dest->cck)); + val = mt76_get_of_array_s8(np, "rates-cck", &len, ARRAY_SIZE(dest->cck)); mt76_apply_array_limit(dest->cck, ARRAY_SIZE(dest->cck), val, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-ofdm", - &len, ARRAY_SIZE(dest->ofdm)); + val = mt76_get_of_array_s8(np, "rates-ofdm", + &len, ARRAY_SIZE(dest->ofdm)); mt76_apply_array_limit(dest->ofdm, ARRAY_SIZE(dest->ofdm), val, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-mcs", &len, mcs_rates + 1); + val = mt76_get_of_array_s8(np, "rates-mcs", &len, mcs_rates + 1); mt76_apply_multi_array_limit(dest->mcs[0], ARRAY_SIZE(dest->mcs[0]), ARRAY_SIZE(dest->mcs), val, len, target_power, txs_delta, &max_power); - val = mt76_get_of_array(np, "rates-ru", &len, ru_rates + 1); + val = mt76_get_of_array_s8(np, "rates-ru", &len, ru_rates + 1); mt76_apply_multi_array_limit(dest->ru[0], ARRAY_SIZE(dest->ru[0]), ARRAY_SIZE(dest->ru), val, len, target_power, txs_delta, &max_power);

1 week, 3 days

FAILED: patch "[PATCH] sched/eevdf: Fix min_vruntime vs avg_vruntime" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 79f3f9bedd149ea438aaeb0fb6a083637affe205 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122902-untreated-unbiased-5922@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 79f3f9bedd149ea438aaeb0fb6a083637affe205 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra <peterz(a)infradead.org> Date: Wed, 2 Apr 2025 20:07:34 +0200 Subject: [PATCH] sched/eevdf: Fix min_vruntime vs avg_vruntime Basically, from the constraint that the sum of lag is zero, you can infer that the 0-lag point is the weighted average of the individual vruntime, which is what we're trying to compute: \Sum w_i * v_i avg = -------------- \Sum w_i Now, since vruntime takes the whole u64 (worse, it wraps), this multiplication term in the numerator is not something we can compute; instead we do the min_vruntime (v0 henceforth) thing like: v_i = (v_i - v0) + v0 This does two things: - it keeps the key: (v_i - v0) 'small'; - it creates a relative 0-point in the modular space. If you do that subtitution and work it all out, you end up with: \Sum w_i * (v_i - v0) avg = --------------------- + v0 \Sum w_i Since you cannot very well track a ratio like that (and not suffer terrible numerical problems) we simpy track the numerator and denominator individually and only perform the division when strictly needed. Notably, the numerator lives in cfs_rq->avg_vruntime and the denominator lives in cfs_rq->avg_load. The one extra 'funny' is that these numbers track the entities in the tree, and current is typically outside of the tree, so avg_vruntime() adds current when needed before doing the division. (vruntime_eligible() elides the division by cross-wise multiplication) Anyway, as mentioned above, we currently use the CFS era min_vruntime for this purpose. However, this thing can only move forward, while the above avg can in fact move backward (when a non-eligible task leaves, the average becomes smaller), this can cause trouble when through happenstance (or construction) these values drift far enough apart to wreck the game. Replace cfs_rq::min_vruntime with cfs_rq::zero_vruntime which is kept near/at avg_vruntime, following its motion. The down-side is that this requires computing the avg more often. Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy") Reported-by: Zicheng Qu <quzicheng(a)huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Link: https://patch.msgid.link/20251106111741.GC4068168@noisy.programming.kicks-a… Cc: stable(a)vger.kernel.org diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 02e16b70a790..41caa22e0680 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -796,7 +796,7 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu) void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) { - s64 left_vruntime = -1, min_vruntime, right_vruntime = -1, left_deadline = -1, spread; + s64 left_vruntime = -1, zero_vruntime, right_vruntime = -1, left_deadline = -1, spread; struct sched_entity *last, *first, *root; struct rq *rq = cpu_rq(cpu); unsigned long flags; @@ -819,15 +819,15 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) last = __pick_last_entity(cfs_rq); if (last) right_vruntime = last->vruntime; - min_vruntime = cfs_rq->min_vruntime; + zero_vruntime = cfs_rq->zero_vruntime; raw_spin_rq_unlock_irqrestore(rq, flags); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "left_deadline", SPLIT_NS(left_deadline)); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "left_vruntime", SPLIT_NS(left_vruntime)); - SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "min_vruntime", - SPLIT_NS(min_vruntime)); + SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "zero_vruntime", + SPLIT_NS(zero_vruntime)); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "avg_vruntime", SPLIT_NS(avg_vruntime(cfs_rq))); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "right_vruntime", diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4a11a832d63e..8d971d48669f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -554,7 +554,7 @@ static inline bool entity_before(const struct sched_entity *a, static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se) { - return (s64)(se->vruntime - cfs_rq->min_vruntime); + return (s64)(se->vruntime - cfs_rq->zero_vruntime); } #define __node_2_se(node) \ @@ -606,13 +606,13 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se) * * Which we track using: * - * v0 := cfs_rq->min_vruntime + * v0 := cfs_rq->zero_vruntime * \Sum (v_i - v0) * w_i := cfs_rq->avg_vruntime * \Sum w_i := cfs_rq->avg_load * - * Since min_vruntime is a monotonic increasing variable that closely tracks - * the per-task service, these deltas: (v_i - v), will be in the order of the - * maximal (virtual) lag induced in the system due to quantisation. + * Since zero_vruntime closely tracks the per-task service, these + * deltas: (v_i - v), will be in the order of the maximal (virtual) lag + * induced in the system due to quantisation. * * Also, we use scale_load_down() to reduce the size. * @@ -671,7 +671,7 @@ u64 avg_vruntime(struct cfs_rq *cfs_rq) avg = div_s64(avg, load); } - return cfs_rq->min_vruntime + avg; + return cfs_rq->zero_vruntime + avg; } /* @@ -732,7 +732,7 @@ static int vruntime_eligible(struct cfs_rq *cfs_rq, u64 vruntime) load += weight; } - return avg >= (s64)(vruntime - cfs_rq->min_vruntime) * load; + return avg >= (s64)(vruntime - cfs_rq->zero_vruntime) * load; } int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se) @@ -740,42 +740,14 @@ int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se) return vruntime_eligible(cfs_rq, se->vruntime); } -static u64 __update_min_vruntime(struct cfs_rq *cfs_rq, u64 vruntime) +static void update_zero_vruntime(struct cfs_rq *cfs_rq) { - u64 min_vruntime = cfs_rq->min_vruntime; - /* - * open coded max_vruntime() to allow updating avg_vruntime - */ - s64 delta = (s64)(vruntime - min_vruntime); - if (delta > 0) { - avg_vruntime_update(cfs_rq, delta); - min_vruntime = vruntime; - } - return min_vruntime; -} + u64 vruntime = avg_vruntime(cfs_rq); + s64 delta = (s64)(vruntime - cfs_rq->zero_vruntime); -static void update_min_vruntime(struct cfs_rq *cfs_rq) -{ - struct sched_entity *se = __pick_root_entity(cfs_rq); - struct sched_entity *curr = cfs_rq->curr; - u64 vruntime = cfs_rq->min_vruntime; + avg_vruntime_update(cfs_rq, delta); - if (curr) { - if (curr->on_rq) - vruntime = curr->vruntime; - else - curr = NULL; - } - - if (se) { - if (!curr) - vruntime = se->min_vruntime; - else - vruntime = min_vruntime(vruntime, se->min_vruntime); - } - - /* ensure we never gain time by being placed backwards. */ - cfs_rq->min_vruntime = __update_min_vruntime(cfs_rq, vruntime); + cfs_rq->zero_vruntime = vruntime; } static inline u64 cfs_rq_min_slice(struct cfs_rq *cfs_rq) @@ -848,6 +820,7 @@ RB_DECLARE_CALLBACKS(static, min_vruntime_cb, struct sched_entity, static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) { avg_vruntime_add(cfs_rq, se); + update_zero_vruntime(cfs_rq); se->min_vruntime = se->vruntime; se->min_slice = se->slice; rb_add_augmented_cached(&se->run_node, &cfs_rq->tasks_timeline, @@ -859,6 +832,7 @@ static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) rb_erase_augmented_cached(&se->run_node, &cfs_rq->tasks_timeline, &min_vruntime_cb); avg_vruntime_sub(cfs_rq, se); + update_zero_vruntime(cfs_rq); } struct sched_entity *__pick_root_entity(struct cfs_rq *cfs_rq) @@ -1226,7 +1200,6 @@ static void update_curr(struct cfs_rq *cfs_rq) curr->vruntime += calc_delta_fair(delta_exec, curr); resched = update_deadline(cfs_rq, curr); - update_min_vruntime(cfs_rq); if (entity_is_task(curr)) { /* @@ -3808,15 +3781,6 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, if (!curr) __enqueue_entity(cfs_rq, se); cfs_rq->nr_queued++; - - /* - * The entity's vruntime has been adjusted, so let's check - * whether the rq-wide min_vruntime needs updated too. Since - * the calculations above require stable min_vruntime rather - * than up-to-date one, we do the update at the end of the - * reweight process. - */ - update_min_vruntime(cfs_rq); } } @@ -5429,15 +5393,6 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) update_cfs_group(se); - /* - * Now advance min_vruntime if @se was the entity holding it back, - * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be - * put back on, and if we advance min_vruntime, we'll be placed back - * further than we started -- i.e. we'll be penalized. - */ - if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE) - update_min_vruntime(cfs_rq); - if (flags & DEQUEUE_DELAYED) finish_delayed_dequeue_entity(se); @@ -9015,7 +8970,6 @@ static void yield_task_fair(struct rq *rq) if (entity_eligible(cfs_rq, se)) { se->vruntime = se->deadline; se->deadline += calc_delta_fair(se->slice, se); - update_min_vruntime(cfs_rq); } } @@ -13078,23 +13032,6 @@ static inline void task_tick_core(struct rq *rq, struct task_struct *curr) * Which shows that S and s_i transform alike (which makes perfect sense * given that S is basically the (weighted) average of s_i). * - * Then: - * - * x -> s_min := min{s_i} (8) - * - * to obtain: - * - * \Sum_i w_i (s_i - s_min) - * S = s_min + ------------------------ (9) - * \Sum_i w_i - * - * Which already looks familiar, and is the basis for our current - * approximation: - * - * S ~= s_min (10) - * - * Now, obviously, (10) is absolute crap :-), but it sorta works. - * * So the thing to remember is that the above is strictly UP. It is * possible to generalize to multiple runqueues -- however it gets really * yuck when you have to add affinity support, as illustrated by our very @@ -13116,23 +13053,23 @@ static inline void task_tick_core(struct rq *rq, struct task_struct *curr) * Let, for our runqueue 'k': * * T_k = \Sum_i w_i s_i - * W_k = \Sum_i w_i ; for all i of k (11) + * W_k = \Sum_i w_i ; for all i of k (8) * * Then we can write (6) like: * * T_k - * S_k = --- (12) + * S_k = --- (9) * W_k * * From which immediately follows that: * * T_k + T_l - * S_k+l = --------- (13) + * S_k+l = --------- (10) * W_k + W_l * * On which we can define a combined lag: * - * lag_k+l(i) := S_k+l - s_i (14) + * lag_k+l(i) := S_k+l - s_i (11) * * And that gives us the tools to compare tasks across a combined runqueue. * @@ -13143,7 +13080,7 @@ static inline void task_tick_core(struct rq *rq, struct task_struct *curr) * using (7); this only requires storing single 'time'-stamps. * * b) when comparing tasks between 2 runqueues of which one is forced-idle, - * compare the combined lag, per (14). + * compare the combined lag, per (11). * * Now, of course cgroups (I so hate them) make this more interesting in * that a) seems to suggest we need to iterate all cgroup on a CPU at such @@ -13191,12 +13128,11 @@ static inline void task_tick_core(struct rq *rq, struct task_struct *curr) * every tick. This limits the observed divergence due to the work * conservancy. * - * On top of that, we can improve upon things by moving away from our - * horrible (10) hack and moving to (9) and employing (13) here. + * On top of that, we can improve upon things by employing (10) here. */ /* - * se_fi_update - Update the cfs_rq->min_vruntime_fi in a CFS hierarchy if needed. + * se_fi_update - Update the cfs_rq->zero_vruntime_fi in a CFS hierarchy if needed. */ static void se_fi_update(const struct sched_entity *se, unsigned int fi_seq, bool forceidle) @@ -13210,7 +13146,7 @@ static void se_fi_update(const struct sched_entity *se, unsigned int fi_seq, cfs_rq->forceidle_seq = fi_seq; } - cfs_rq->min_vruntime_fi = cfs_rq->min_vruntime; + cfs_rq->zero_vruntime_fi = cfs_rq->zero_vruntime; } } @@ -13263,11 +13199,11 @@ bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b, /* * Find delta after normalizing se's vruntime with its cfs_rq's - * min_vruntime_fi, which would have been updated in prior calls + * zero_vruntime_fi, which would have been updated in prior calls * to se_fi_update(). */ delta = (s64)(sea->vruntime - seb->vruntime) + - (s64)(cfs_rqb->min_vruntime_fi - cfs_rqa->min_vruntime_fi); + (s64)(cfs_rqb->zero_vruntime_fi - cfs_rqa->zero_vruntime_fi); return delta > 0; } @@ -13513,7 +13449,7 @@ static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first) void init_cfs_rq(struct cfs_rq *cfs_rq) { cfs_rq->tasks_timeline = RB_ROOT_CACHED; - cfs_rq->min_vruntime = (u64)(-(1LL << 20)); + cfs_rq->zero_vruntime = (u64)(-(1LL << 20)); raw_spin_lock_init(&cfs_rq->removed.lock); } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 82e74e8ca2ea..5a3cf81c27be 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -681,10 +681,10 @@ struct cfs_rq { s64 avg_vruntime; u64 avg_load; - u64 min_vruntime; + u64 zero_vruntime; #ifdef CONFIG_SCHED_CORE unsigned int forceidle_seq; - u64 min_vruntime_fi; + u64 zero_vruntime_fi; #endif struct rb_root_cached tasks_timeline;

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